XSLT and XQuery Serialization 4.0

REC-xslt-xquery-serialization-40

W3C Editor's Draft

28January2026 https://qt4cg.org/2026-01-28/xslt-xquery-serialization-40/ XML https://qt4cg.org/specifications/xslt-xquery-serialization-40/ https://www.w3.org/TR/xslt-xquery-serialization-31/ Michael KaySaxonicahttp://www.saxonica.com/

This section describes the status of this document at the time of its publication. Other documents may supersede this document.

This document is a working draft developed and maintained by a W3C Community Group, the XQuery and XSLT Extensions Community Group unofficially known as QT4CG (where "QT" denotes Query and Transformation). This draft is work in progress and should not be considered either stable or complete. Standard W3C copyright and patent conditions apply.

This draft is a snapshot of the specification representing the consensus of the Community Group at the time of publication. It is published with a dated URL and will remain available at that URL so that users and implementors can refer to this as a versioned draft, confident that it won’t change. However, the work is not finished, and the specification is under active development. For links to the most recent specifications, see .

The community group welcomes comments on the specification. Comments are best submitted as issues on the group's GitHub repository.

The community group maintains two extensive test suites, one oriented to XQuery and XPath, the other to XSLT. These can be found at qt4tests and xslt40-test respectively. New tests, or suggestions for correcting existing tests, are welcome. The test suites include extensive metadata describing the conditions for applicability of each test case as well as the expected results. They do not include any test drivers for executing the tests: each implementation is expected to provide its own test driver.

The publications of this community group are dedicated to our co-chair, Michael Sperberg-McQueen (1954–2024).

This document defines methods of serializing an instance of the data model defined in into a sequence of octets, conforming to a variety of formats including XML, HTML, and JSON. Serialization is designed to be a component that can be used either on its own, or invoked from languages such as , or .

English

IntroductionIf a section of this specification has been updated since version 3.1, an overview of the changes is provided, along with links to navigate to the next or previous change.Sections with significant changes are marked with a ✭ symbol in the table of contents.

This document defines methods of serializing the W3C XQuery and XPath Data Model 4.0 (), that is, methods of representing instances of the data model as strings or octet sequences. This is the data model used by , , and , and any other specifications that reference it.

In this document, examples and material labeled as Note are provided for explanatory purposes and are not normative.

Serialization is the process of converting an instance of the into a sequence of octets.

The XDM value supplied as input to the serializer is referred to as the input value. Some serialization methods apply only to certain types of input value.

Where serialization is used to process the result of an XQuery evaluation or an XSLT transformation, the of the serializer corresponds to the output from XQuery or XSLT.

In general the output of the serializer will represent the items actually present in the input value, together with other items that are reachable from these, for example (in the case of nodes) their descendants. The complete set of items that are represented in the output of the serializer is referred to (without loss of generality) as the input tree.

Terminology The term atomic value has been replaced by atomic item.

In this specification, where they are rendered in small capitals, the words MUST, MUST NOT, SHOULD, SHOULD NOT, MAY, REQUIRED, and RECOMMENDED are to be interpreted as described in .

As is indicated in , conformance criteria for serialization are determined by other specifications that refer to this specification. A serializer is software that implements some or all of the requirements of this specification in accordance with such conformance criteria. A serializer is not REQUIRED to directly provide a programming interface that permits a user to set serialization parameters or to provide an input sequence for serialization. In this document, material labeled as "Note" and examples are provided for explanatory purposes and are not normative.

Certain aspects of serialization are described in this specification as implementation-defined or implementation-dependent.

Implementation-defined indicates an aspect that MAY differ between serializers, but whose actual behavior MUST be specified either by another specification that sets conformance criteria for serialization (see ) or in documentation that accompanies the serializer.

Implementation-dependent indicates an aspect that MAY differ between serializers, and whose actual behavior is not REQUIRED to be specified either by another specification that sets conformance criteria for serialization (see ) or in documentation that accompanies the serializer.

In some instances, the cannot be successfully converted into a sequence of octets given the set of serialization parameter () values specified. A serialization error is said to occur in such an instance. In some cases, a serializer is REQUIRED to raise such an error. What it means to raise a serialization error is determined by the relevant conformance criteria () to which the serializer conforms. In other cases, there is an implementation-defined choice between raising a serialization error and performing a recovery action. Such a recovery action will allow a serializer to produce a sequence of octets that might not fully reflect the usual requirements of the parameter settings that are in effect.

Where this specification indicates that two strings are to be compared without regard to case, the serializer MUST translate any characters in the range U+0041 through U+005A inclusive, to the corresponding lower-case letters in the range U+0061 through U+007A only for the purposes of making the comparison. The comparison succeeds if the two strings are the same length and the code point of each character in the first string is equal to the code point of the character in the corresponding position in the second string.

Many terms used in this document are defined in the XPath specification or the Data Model specification . Particular attention is drawn to the following:

The term atomization is defined in .

The term node is defined in . There are seven kinds of nodes in the data model: document, element, attribute, text, namespace, processing instruction, and comment.

The term sequence is defined in . A sequence is an ordered collection of zero or more items.

The term function item is defined in .

The term map item is defined in .

The term array item is defined in .

The term string is defined in .

The term character is defined in .

The term codepoint is defined in .

The term string value is defined in . Every node has a string value. For example, the string value of an element is the concatenation of the string values of all its descendant text nodes.

The term expanded QName is defined in . An expanded QName consists of an optional namespace URI and a local name. An expanded QName also retains its original namespace prefix (if any), to facilitate casting the expanded QName into a string.

An expanded-QName whose namespace part is an empty sequence, or an element or attribute whose name expands to such an expanded-QName, is referred to as having a null namespace URI.

An element or attribute that does not have a null namespace URI, is referred to as having a non-null namespace URI.

A space character, TAB character, CR character or NL character is referred to as a whitespace character.

Where this specification indicates that an XSLT instruction is evaluated, the behavior is as specified by . Where it indicates that an XQuery expression is evaluated, the behavior is as specified by .

Namespaces

This specification refers to several namespaces that affect the process of serialization. These are:

the Output declaration namespace, https://www.w3.org/2010/xslt-xquery-serialization;

the XML namespace, https://www.w3.org/XML/1998/namespace;

the XHTML namespace namespace, https://www.w3.org/1999/xhtml;

the SVG namespace, https://www.w3.org/2000/svg; and

the MathML namespace namespace, https://www.w3.org/1998/Math/MathML.

Wherever an element node or attribute node is said to be in a particular namespace, it is understood that the namespace URI of the node is equal to the namespace URI corresponding to that namespace. Wherever a namespace node is said to be a namespace node for a particular namespace, it is understood that the string value of the node is equal to the namespace URI corresponding to that namespace.

Sequence Normalization

The is a sequence. Prior to serializing a sequence using any of the output methods whose behavior is specified by this document (), with the exception of the JSON and Adaptive output methods, the serializer MUST first compute a normalized sequence for serialization; it is the normalized sequence that is actually serialized. The purpose of sequence normalization is to create a sequence that can be serialized as a well-formed XML document or external general parsed entity, that also reflects the content of the input sequence to the extent possible. The result of the sequence normalization process is a result tree.

The normalized sequence for serialization is constructed by applying all of the following rules in order, with the being input to the first step, and the sequence that results from any step being used as input to the subsequent step. For any implementation-defined output method, it is implementation-defined whether this sequence normalization process takes place. For the JSON and Adaptive output methods, sequence normalization MUST NOT take place.

For any implementation-defined output method, it is implementation-defined whether sequence normalization process takes place.

Where the process of converting the input sequence to a normalized sequence indicates that a value MUST be cast to xs:string, that operation is defined in of . Where a step in the sequence normalization process indicates that a node should be copied, the copy is performed in the same way as an XSLT xsl:copy-of instruction that has a validation attribute whose value is preserve and has a select attribute whose effective value is the node, as described in of , or equivalently in the same way as an XQuery content expression as described in Step 1e of of , where the construction mode is preserve. Let S0 be the sequence that is input to serialization. The steps in computing the normalized sequence are:

Create a new sequence S1 from S0 as follows. For each item in S0, if the item is a JNode, copy the ·content· property of the item; otherwise, copy the item itself.

Create a new sequence S2 from S1 as follows. For each item in S1, if the item is an array, copy the results of passing the item into the function array:flatten(); otherwise, copy the item itself. If S1 is empty, let S2 consist of a zero-length string.

Create a new sequence S3 from S2 as follows. For each item in S3, if the item is atomic, copy to S3 only the lexical representation resulting from casting the item to an xs:string, otherwise, copy the item to S3.

Create a new sequence S4 from S3 as follows. If the item-separator serialization parameter is present, then copy each item in S3 to S4, inserting between each pair of items a string whose value is equal to the value of the item-separator parameter. If the item-separator serialization parameter is not present, then first maximally group the items in S3 into subsequences of xs:string items and non-xs:string items. For each group of items, if the group is a subsequence of non-xs:string items, copy the subsequence to S4; if the group is a subsequence of xs:string items, copy to S4 the results of passing to fn:string-join() the subsequence and the value of item-separator as the function’s two parameters.

Create a new sequence S5 from S4 as follows. For each item in S4, if the item is a string, copy to S5 a text node whose string value is equal to the string; otherwise, copy the item to S5.

Create a new sequence S6 from S5 as follows. For each item in S5, if the item is a document node, copy its children to S6; otherwise, copy the item to S6.

Create a new sequence S7 from S6 as follows. First, remove any text nodes with values of zero length from S6, then maximally group the results into groups of text nodes and non-text nodes. For each group of items, if the group is a subsequence of text nodes, copy to S7 a single text node whose value is equal to the concatenated values of the subsequence; if the group is a subsequence of non-text nodes, copy the subsequence of items to S7. It is a serialization error if any item in S7 is an attribute node, a namespace node, or a function.

Create a new sequence S8 from S7 as follows. Let S8 be a single document node. Copy sequence S7 to the document node as its children.

S8 is the normalized sequence.

The result tree rooted at the document node that is created by the final step of this sequence normalization process is the value to which the rules of the appropriate output method are applied. If the sequence normalization process results in a serialization error, the serializer MUST raise the error.

If the item-separator serialization parameter is absent, the sequence normalization process for a sequence $seq is equivalent to constructing a document node using the XSLT instruction:

<xsl:document> <xsl:copy-of select="$seq" validation="preserve"/> </xsl:document>

or the XQuery expression:

declare construction preserve; document { $seq }

If the item-separator serialization parameter is present, the sequence normalization process for a sequence $seq is equivalent to constructing a document node using the XSLT instruction:

<xsl:document> <xsl:for-each select="$seq"> <xsl:sequence select="if (position() gt 1) then $sep else ()"/> <xsl:choose> <xsl:when test=". instance of node()"> <xsl:sequence select="."/> </xsl:when> <xsl:otherwise> <xsl:value-of select="."/> </xsl:otherwise> </xsl:choose> </xsl:for-each> </xsl:document>

or the XQuery expression:

declare construction preserve; document { for $item at $pos in $seq let $node := if ($item instance of node()) then $item else text { $item } return if ($pos eq 1) then $node else ($sep, $node) }

where the value of the sep variable is a string whose value is equal to the value of the item-separator serialization parameter.

This process results in a serialization error if $seq contains functions, attribute nodes or namespace nodes.

Serialization Parameters Added the escape-solidus parameter for JSON serialization. Added the json-lines parameter for JSON serialization. Added the canonical parameter for XML, XHTML, and JSON serialization.

There are a number of parameters that influence how serialization is performed. Host languages MAY allow users to specify any or all of these parameters, but they are not REQUIRED to be able to do so. However, the host language specification MUST specify how the values of all applicable parameters are to be determined.

Host languages may also define alternative representations of the values of serialization parameters. For example, both XSLT and XQuery allow the boolean values true and false to be written as 1/0 or yes/no. The $options map passed to the fn:serialize function, by contrast, requires an xs:boolean value.

It is a serialization error if a parameter value is invalid for the given parameter. It is the responsibility of the host language to specify how invalid values should be handled at the level of that language.

The following serialization parameters are defined:

Serialization parameter name	Permitted values for parameter
`allow-duplicate-names`	A boolean value, `true` or `false`. This parameter indicates whether a map item serialized as a JSON object using the JSON output method is allowed to contain duplicate member names. If the value `false` is specified, a serialization error may be raised under certain conditions.
`byte-order-mark`	A boolean value, `true` or `false`. This parameter indicates whether the serialized sequence of octets is to be preceded by a Byte Order Mark (See Section 5.1 of ). The actual octet order used is implementation-dependent. If the encoding defines no Byte Order Mark, or if the Byte Order Mark is prohibited for the specific encoding or implementation environment, then this parameter is ignored.
`canonical`	A boolean value, `true` or `false`.
`cdata-section-elements`	A list of expanded QNames, possibly empty.
`doctype-public`	A string of PubidChar characters. This parameter MAY be absent.
`doctype-system`	A string of Unicode characters that does not include both the characters U+0027 and U+0022. This parameter MAY be absent.
`encoding`	A string of Unicode characters in the range U+0021 through U+007E (that is, printable ASCII characters); the value SHOULD be a charset registered with the Internet Assigned Numbers Authority , or begin with the characters `x-` or `X-`.
`escape-solidus`	A boolean value, `true` or `false`.
`escape-uri-attributes`	A boolean value, `true` or `false`.
`html-version`	A decimal value. This parameter MAY be absent.
`include-content-type`	A boolean value, `true` or `false`.
`indent`	A boolean value, `true` or `false`.
`item-separator`	A string of Unicode characters. This parameter MAY be absent.
`json-lines`	A boolean value, `true` or `false`.
`json-node-output-method`	An expanded QName with a non-null namespace URI, or with a null namespace URI and a local name equal to one of `xml`, `xhtml`, `html` or `text`. If the namespace URI is non-null, the parameter specifies an implementation-defined output method.
`media-type`	A string of Unicode characters specifying the media type (MIME content type) ; the charset parameter of the media type MUST NOT be specified explicitly in the value of the `media-type` parameter. If the destination of the serialized output is annotated with a media type, this parameter MAY be used to provide such an annotation. For example, it MAY be used to set the media type in an HTTP header.
`method`	An expanded QName with a non-null namespace URI, or with a null namespace URI and a local name that MUST be equal to one of `xml`, `xhtml`, `html`, `text`, `json`, or `adaptive`, in which case, the output method specified MUST be used for serializing. If the namespace URI is non-null, the parameter specifies an implementation-defined output method; its behavior is not specified by this document.
`normalization-form`	One of the enumerated values `NFC`, `NFD`, `NFKC`, `NFKD`, `fully-normalized` or `none`, or an implementation-defined value of type `NMTOKEN`.
`omit-xml-declaration`	A boolean value, `true` or `false`.
`standalone`	Either a boolean value, `true` or `false`, or the value or `omit`.
`suppress-indentation`	A list of expanded QNames, possibly empty.
`undeclare-prefixes`	A boolean value, `true` or `false`.
`use-character-maps`	A list of pairs, possibly empty, with each pair consisting of a single Unicode character and a string of Unicode characters.
`version`	A string of Unicode characters. This parameter MAY be absent.

The octet order of the serialized result sequence of octets is implementation-dependent.

If the namespace URI is non-null for the method serialization parameter, then the parameter specifies an implementation-defined output method.

In those cases where they have no important effect on the content of the serialized result, details of the output methods defined by this specification are left unspecified and are regarded as implementation-dependent. Whether a serializer uses apostrophes or quotation marks to delimit attribute values in the XML output method is an example of such a detail.

The detailed semantics of each parameter will be described separately for each output method for which it is applicable. If the semantics of a parameter are not described for an output method, then it is not applicable to that output method.

Implementations MAY define additional serialization parameters, and MAY allow users to do so. For this purpose, the name of a serialization parameter is considered to be a QName; the parameters listed above are QNames whose expanded-QName has a null namespace URI, while any additional serialization parameters that are either implementation-defined or defined by the host language MUST have names that are namespace-qualified. Any such additional serialization parameters MUST NOT be in the namespace https://www.w3.org/2010/xslt-xquery-serialization. A host language MAY specify the means by which an implementation can define such an additional serialization parameter, and implementations MAY provide mechanisms by which users can define such an additional serialization parameter. If the serialization method is one of the six methods xml, html, xhtml, text, json, or adaptive then the additional serialization parameters MAY affect the output of the serializer to the extent (but only to the extent) that this specification leaves the output implementation-defined or implementation-dependent. For example, such parameters might control whether namespace declarations on an element are written before or after the attributes of the element, or they might define the number of space or tab characters to be inserted when the indent parameter is set to true; but they could not instruct the serializer to suppress the error that occurs when the HTML output method encounters characters that are not permitted (see error ).

The effect of additional serialization parameters on the output of the serializer, where the name of such a parameter MUST be namespace-qualified, is implementation-defined or implementation-dependent. The extent of this effect on the output MUST NOT override the provisions of this specification.

Setting Serialization Parameters by Means of a Parameter Document

A host language MAY provide, by reference to this section, a mechanism by which the settings of serialization parameters are supplied in the form of an output:serialization-parameters element node.

An output:serialization-parameters element node used to hold the settings of serialization parameters is referred to as a parameter document.

The use of the word document does not imply that the output:serialization-parameters element must be the outermost element of an XDM document, although this will often be the case.

The MUST be processed as if by the procedure described below.

With the exception of the use-character-maps parameter, the setting of each serialization parameter defined in this specification is equal to the result of evaluating the XQuery expression

document { . } /output:serialization-parameters /(validate lax { output:*[local-name() eq $param-name] }) /data(@value)

or equivalently the XSLT instructions

<xsl:sequence> <xsl:variable name="validated-instance"> <xsl:document validation="lax"> <xsl:sequence select=" self::output:serialization-parameters /output:* [local-name() eq $param-name]"/> </xsl:document> </xsl:variable> <xsl:sequence select="$validated-instance /data(@value)"/> </xsl:sequence>

with the as the context value, the param-name variable bound to a value of type xs:string equal to the local part of the name of the particular serialization parameter, and the other components of the dynamic context and static context as specified in the subsequent tables. If in any case evaluating this expression would yield an error, serialization error results.

If the result of evaluating this expression for a particular serialization parameter is the empty sequence, then

If the parameter is either cdata-section-elements or suppress-indentation, and the result of evaluating the XQuery expression

document { . } /output:serialization-parameters /(validate lax { output:*[local-name() eq $param-name] })

or equivalently the XSLT instructions

<xsl:sequence> <xsl:variable name="validated-instance"> <xsl:document select="." validation="lax"> <xsl:sequence select=" self::output:serialization-parameters /output:* [local-name() eq $param-name]"/> </xsl:document> </xsl:variable> <xsl:sequence select="$validated-instance"/> </xsl:sequence>

with the same settings of the static context and dynamic context is not an empty sequence, the setting of the parameter is the empty list;

otherwise, the setting of the parameter is absent.

The components of the static context used in evaluating the XQuery expressions or XSLT instructions are as defined in the following table.

Static Context Component	XQuery or XSLT	Setting
XPath 1.0 compatibility mode	Both	false
Statically known namespaces	XQuery	The pair (output,http://www.w3.org/2010/xslt-xquery-serialization)
Statically known namespaces	XSLT	The pairs (output,http://www.w3.org/2010/xslt-xquery-serialization), (xsl,http://www.w3.org/1999/XSL/Transform)
Default element/type namespace	Both	"none"
Default function namespace	Both	http://www.w3.org/2005/xpath-functions
In-scope schema types, In-scope element declarations, Substitution groups, In-scope attribute declarations	Both	As defined by the schema for serialization parameters () and any additional implementation-defined in-scope schema components
In-scope variables	Both	{param-name}
Context value static type	Both	`node()`
Statically known function signatures	Both	{`fn:data($arg as item()) as xs:anyAtomicType`}, {`fn:local-name($arg as node()?) as xs:string`}
Statically known collations	Both	{ (http://www.w3.org/2005/xpath-functions/collation/codepoint, The Unicode codepoint collation ) }
Default collation	Both	The Unicode codepoint collation
Construction mode	XQuery	strip
Ordering mode	XQuery	ordered
Default order for empty sequences	XQuery	least
Boundary space policy	XQuery	strip
Copy-namespaces mode	XQuery	(preserve,inherit)
Base URI	Both	Absent
Statically known documents	Both	None
Statically known collections	Both	None
Statically known default collection type	Both	`node()*`
Statically known decimal formats	Both	None
Set of named keys	XSLT	{}
Values of system properties	XSLT	None
Set of available instructions	XSLT	The set of all instructions defined by

Implementation-defined schema components MAY be included in the set of schema components that are used in evaluating an XQuery expression or XSLT instruction in the process of using a to determine the serialization parameters.

The remaining components of the dynamic context used in evaluating the XQuery expressions or XSLT instructions in the preceding table are as defined in the following table.

Dynamic Context Component	XQuery or XSLT	Setting
Context position	Both	1
Context size	Both	1
Variable values	Both	The `param-name` variable has a value of type `xs:string` equal to the local part of the name of the serialization parameter under consideration
Function implementations	Both	The implementation of `fn:data`
Current dateTime	Both	Absent
Implicit timezone	Both	Absent
Available documents	Both	None
Available collections	Both	None
Default collection	Both	None
Current template rule	XSLT	Absent
Current mode	XSLT	The default mode
Current group	XSLT	Absent
Current grouping key	XSLT	Absent
Current captured substrings	XSLT	The empty sequence
Output state	XSLT	Temporary output state

In the case of the use-character-maps parameter, the XQuery expression

document { . } /output:serialization-parameters / ( validate lax { output:use-character-maps } ) /output:character-map[@character eq $char] /string(@map-string)

or equivalently the XSLT instructions

<xsl:sequence> <xsl:variable name="validated-instance"> <xsl:document validation="lax"> <xsl:sequence select=" self::output:serialization-parameters /output:use-character-maps"/> </xsl:document> </xsl:variable> <xsl:sequence select="$validated-instance /output:character-map [@character eq $char] /string(@map-string)"/> </xsl:sequence>

is evaluated for each Unicode character that is permitted in an XML document. The dynamic context and static context used to evaluate the expression are as defined above, except that the component In-scope variables is the set {char} and the value of the variable "char" is a value of type xs:string of length one whose value is the Unicode character under consideration. If the result of evaluating the expression is not an empty sequence, the pair consisting of the Unicode character and the result of evaluating the expression is part of the list of pairs in the value of the use-character-maps parameter. It is a serialization error if the result of evaluating this expression for any character is a sequence of length greater than one.

Using the same settings of the components of the dynamic context and static context, serialization error results if the result of evaluating the following XQuery expression is not true

(document { . })/output:serialization-parameters /(count(distinct-values(*/node-name(.))) eq (count(*)))

or equivalently if the result of evaluating the following XSLT instructions is not true.

<xsl:sequence> <xsl:variable name="doc"> <xsl:document> <xsl:sequence select="."/> </xsl:document> </xsl:variable> <xsl:sequence select="$doc/output:serialization-parameters /(count(distinct-values( */node-name(.))) eq (count(*)))"/> </xsl:sequence>

The result of evaluating either will be false if the supplies a value for any particular serialization parameter more than once, or will be the empty sequence if the is not an element node whose local name is serialization-parameters and whose namespace URI is http://www.w3.org/2010/xslt-xquery-serialization.

A serializer or implementation of a host language does not need to be accompanied by an XQuery processor nor by a general-purpose schema validator in order to meet the requirements of this section. It merely needs to be capable of extracting values from an XDM instance that conforms to the schema for serialization parameters, while checking that the constraints implied by the schema and additional constraints implied by the XQuery validate expression or explicitly stated in this section are satisfied.

The host language MAY provide additional mechanisms for overriding the values of any serialization parameters specified through the mechanism defined in this section, as well as additional mechanisms for specifying the values of any serialization parameters whose values are absent after applying the mechanism defined in this section.

If the contains elements or attributes that are in a namespace other than http://www.w3.org/2010/xslt-xquery-serialization, the implementation MAY interpret them to specify the values of implementation-defined serialization parameters in an implementation-defined manner.

If a contains elements or attributes that are in a namespace other than http://www.w3.org/2010/xslt-xquery-serialization, the implementation MAY interpret them to specify the values of implementation-defined serialization parameters in an implementation-defined manner.

The following XML document, if parsed as a and processed using the mechanism described in this section, would specify the settings of the method, version and indent serialization parameters with the values xml, 1.0 and true, respectively.

<output:serialization-parameters xmlns:output = "http://www.w3.org/2010/xslt-xquery-serialization"> <output:method value="xml"/> <output:version value="1.0"/> <output:indent value="yes"/> </output:serialization-parameters>

The following document would specify the value of the cdata-section-elements serialization parameter with value equal to the pair of expanded QNames (http://example.org/book/chapter,heading) and (http://example.org/book,footnote)

<output:serialization-parameters xmlns:output = "http://www.w3.org/2010/xslt-xquery-serialization" xmlns:book="http://example.org/book" xmlns="http://example.org/book/chapter"> <output:cdata-section-elements value="heading book:footnote"/> </output:serialization-parameters>

The following document would specify the value of the method serialization parameter with the value html.

Notice that in this example, the default namespace declaration in scope has no effect on the interpretation of the setting of the method parameter.

<output:serialization-parameters xmlns:output = "http://www.w3.org/2010/xslt-xquery-serialization" xmlns="http://example.org/ext"> <output:method value="html"/> </output:serialization-parameters>

The following document would specify the value of the method serialization parameter with value equal to the expanded QName (http://example.org/ext, jsp), and the use-character-maps parameter with value equal to the list of pairs, («, <%), (», %>).

<output:serialization-parameters xmlns:output = "http://www.w3.org/2010/xslt-xquery-serialization" xmlns:ext="http://example.org/ext"> <output:method value="ext:jsp"/> <output:use-character-maps> <output:character-map character="«" map-string="<%"/> <output:character-map character="»" map-string="%>"/> </output:use-character-maps> </output:serialization-parameters> Phases of Serialization

For the XML, HTML, XHTML and Text output methods, serialization comprises six phases of processing (preceded by the sequence normalization process described in ). For the JSON and Adaptive output methods, serialization is described in and respectively.

For an implementation-defined output method, any of these phases MAY be skipped or MAY be performed in a different order than is specified here. For the output methods defined in this specification, these phases are carried out sequentially as follows:

A meta element is added to the sequence, possibly replacing existing meta elements, as controlled by the include-content-type parameter for the XHTML and HTML output methods. This step is skipped for the other output methods defined by this specification.

Markup generation produces the character representation of those parts of the serialized result that describe the structure of the sequence. In the cases of the XML, HTML and XHTML output methods, this phase produces the character representations of the following:

the document type declaration;

start tags and end tags (except for attribute values, whose representation is produced by the character expansion phase);

processing instructions; and

comments.

In the cases of the XML and XHTML output methods, this phase also produces the following:

the XML or text declaration; and

empty element tags (except for the attribute values);

In the case of the text output method, this phase replaces the single document node produced by sequence normalization with a new document node that has exactly one child, which is a text node. The string value of the new text node is the string value of the document node that was produced by sequence normalization.

Character expansion is concerned with the representation of characters appearing in text and attribute nodes in the sequence. For each text and attribute node, the following rules are applied in sequence.

If the node is an attribute that is a URI attribute value and the escape-uri-attributes parameter is set to require escaping of URI attributes, apply URI escaping as defined below, and skip rules b-e. Otherwise, continue with rule b.

URI escaping consists of the following three steps applied in sequence to the content of URI attribute values:

normalize to NFC using the method defined in

percent-encode any special characters in the URI using the method defined in

escape according to the rules of the XML or HTML output method, whichever is applicable, any characters that require escaping, and any characters that cannot be represented in the selected encoding. For example, replace < with < (See also section ).

The values of attributes listed in are URI attribute values. Attributes are not considered to be URI attributes simply because they are namespace declaration attributes or have the type annotation xs:anyURI.

If the node is a text node whose parent element is selected by the rules of the cdata-section-elements parameter for the applicable output method, create CDATA sections as described below, and skip rules c-e. Otherwise, continue with rule c.

Apply the following two processes in sequence to create CDATA sections

Unicode Normalization if requested by the normalization-form parameter.

The application of changes as detailed in the description of the cdata-section-elements parameter for the applicable output method.

Apply character mapping as determined by the use-character-maps parameter for the applicable output method. For characters that were substituted by this process, skip rules d and e. For the remaining characters that were not modified by character mapping, continue with rule d.

Apply Unicode Normalization if requested by the normalization-form parameter.

Unicode Normalization is the process of removing alternative representations of equivalent sequences from textual data, to convert the data into a form that can be binary-compared for equivalence, as specified in . For specific recommendations for character normalization on the World Wide Web, see .

The meanings associated with the possible values of the normalization-form parameter are defined in section .

Continue with step e.

Escape according to the rules of the XML or HTML output method, whichever is applicable, any characters (such as < and &) where XML or HTML requires escaping, and any characters that cannot be represented in the selected encoding. For example, replace < with <. (See also section ). For characters such as > where XML defines a built-in entity but does not require its use in all circumstances, it is implementation-dependent whether the character is escaped.

Indentation, as controlled by the indent parameter and the suppress-indentation parameter, MAY add or remove whitespace according to the rules defined by the applicable output method.

Encoding, as controlled by the encoding parameter, converts the character sequence produced by the previous phases into an octet stream.

Serialization is defined only in terms of encoding the result as a stream of octets. However, a serializer MAY provide an option that allows the encoding phase to be skipped, so that the result of serialization can be encoded in a way required by a particular destination (e.g., a Java StringBuffer). The effect of any such option is implementation-defined, and a serializer is not required to support such an option.

The effect of providing an option that allows the encoding phase to be skipped, so that the result of serialization can be encoded in a way required by a particular destination (e.g., a Java StringBuffer), is implementation-defined. The serializer is not required to support such an option.

Canonicalization, as controlled by the canonical parameter, MAY revert any previous changes, or make new changes, according to the rules defined by the applicable output method.

XML Output Method

The XML output method serializes the normalized sequence as an XML entity that MUST satisfy the rules for either a well-formed XML document entity, a well-formed XML external general parsed entity, or both. A serialization error results if the serializer is unable to satisfy those rules, except for content modified by the character expansion phase of serialization, as described in . The effects of the character expansion phase could result in the serialized output being not well-formed, but will not result in a serialization error. If a serialization error results, the serializer MUST raise the error.

If the document node of the normalized sequence has a single element node child and no text node children, then the serialized output is a well-formed XML document entity, and the serialized output MUST conform to the appropriate version of the XML Namespaces Recommendation or . If the normalized sequence does not take this form, then the serialized output is a well-formed XML external general parsed entity, which, when referenced within a trivial XML document wrapper like this:

<?xml version="version"?> <!DOCTYPE doc [ <!ENTITY e SYSTEM "entity-URI"> ]> <doc>&e;</doc>

where entity-URI is a URI for the entity, and the value of the version pseudo-attribute is the value of the version parameter, produces a document which MUST itself be a well-formed XML document conforming to the corresponding version of the XML Namespaces Recommendation or .

A reconstructed tree may be constructed by parsing the XML document and converting it into an document node as specified in . The result of serialization MUST be such that the reconstructed tree is the same as the result tree except for the following permitted differences:

If the document was produced by adding a document wrapper, as described above, then it will contain an extra doc element as the document element.

The order of attribute and namespace nodes in the two trees MAY be different.

The following properties of corresponding nodes in the two trees MAY be different:

the base-uri property of document nodes and element nodes;

the document-uri and unparsed-entities properties of document nodes;

the type-name and typed-value properties of element and attribute nodes;

the nilled property of element nodes;

the content property of text nodes, due to the effect of the indent and use-character-maps parameters.

The reconstructed tree MAY contain additional attributes and text nodes resulting from the expansion of default and fixed values in its DTD or schema; also, in the presence of a DTD, non-CDATA attributes may lose whitespace characters as a result of attribute value normalization.

The type annotations of the nodes in the two trees MAY be different. Type annotations in a result tree are discarded when the tree is serialized. Any new type annotations obtained by parsing the document will depend on whether the serialized XML document is assessed against a schema, and this MAY result in type annotations that are different from those in the original result tree.

In order to influence the type annotations in the tree that would result from processing a serialized XML document, the author of the XSLT stylesheet, XQuery expression or other process might wish to create the so that it makes use of mechanisms provided by , such as xsi:type and xsi:schemaLocation attributes. The serialization process will not automatically create such attributes in the serialized document if those attributes were not part of the result tree that is to be serialized.

Similarly, it is possible that an element node in the has the nilled property with the value true, but no xsi:nil attribute. The serialization process will not create such an attribute in the serialized document simply to reflect the value of the property. The value of the nilled property has no direct effect on the serialized result.

Additional namespace nodes MAY be present in the reconstructed tree if the serialization process did not undeclare one or more namespaces, as described in , and the contained an element node with a namespace node that declared some prefix, but a child element of that node did not have any namespace node that declared the same prefix.

The result tree MAY contain namespace nodes that are not present in the reconstructed tree, as the process of creating an instance of the data model MAY ignore namespace declarations in some circumstances. See and of for additional information.

If the indent parameter has the value true,

additional text nodes consisting of whitespace characters MAY be present in the reconstructed tree; and

text nodes in the result tree that contained only whitespace characters MAY correspond to text nodes in the reconstructed tree that contain additional whitespace characters that were not present in the result tree

See for more information on the indent parameter.

Additional nodes MAY be present in the reconstructed tree due to the effect of character mapping in the character expansion phase, and the values of attribute nodes and text nodes in the reconstructed tree MAY be different from those in the result tree, due to the effects of URI expansion, character mapping and Unicode Normalization in the character expansion phase of serialization.

The use-character-maps parameter can cause arbitrary characters to be inserted into the serialized XML document in an unescaped form, including characters that would be considered to be part of XML markup. Such characters could result in arbitrary new element nodes, attribute nodes, and so on, in the reconstructed tree that results from processing the serialized XML document.

A consequence of this rule is that certain characters MUST be output as character references, to ensure that they survive the round trip through serialization and parsing. Specifically:

In text nodes, the characters U+000D, U+0085, and U+2028 MUST be output respectively as "", "", and " ", or their equivalents

In attribute nodes, the characters U+000D, U+000A, U+0009, U+0085, and U+2028 MUST be output respectively as "", "
", "	", "", and " ", or their equivalents.

In both text nodes and attribute nodes, control characters U+0001 through U+001F and U+007F through U+009F (except U+0009, U+000A, and U+000D, and U+0085) MUST be output as character references.

For example, an attribute with the value "x" followed by "y" separated by a newline will result in the output "x
y" (or with any equivalent character reference). The XML output cannot be "x" followed by a literal newline followed by a "y" because after parsing, the attribute value would be "x y" as a consequence of the XML attribute normalization rules.

XML 1.0 did not permit an XML processor to normalize U+0085 or U+2028 characters to a U+000A character. However, if a document entity that specifies version 1.1 invokes an external general parsed entity with no text declaration or a text declaration that specifies version 1.0, the external parsed entity is processed according to the rules of XML 1.1. For this reason, U+0085 and U+2028 characters in text and attribute nodes MUST always be escaped using character references, regardless of the value of the version parameter.

XML 1.0 permitted control characters in the range U+007F through U+009F to appear as literal characters in an XML document, but XML 1.1 requires such characters, other than U+0085, to be escaped as character references. An external general parsed entity with no text declaration or a text declaration that specifies a version pseudo-attribute with value 1.0 that is invoked by an XML 1.1 document entity MUST follow the rules of XML 1.1. Therefore, the non-whitespace control characters in the ranges U+0001 through U+001F and U+007F through U+009F MUST always be escaped, regardless of the value of the version parameter.

It is a serialization error to specify the doctype-system parameter, or to specify the standalone parameter with a value other than omit, if the contains text nodes or multiple element nodes as children of the root node. The serializer MUST either raise the error, or recover by ignoring the request to output a document type declaration or standalone parameter.

The Influence of Serialization Parameters upon the XML Output Method

The serialization parameters that affect the XML output method are listed in the following subsections.

Serialization parameters other than those listed are not applicable to this output method. It is the responsibility of the host language to specify whether an error occurs if such a parameter is specified in combination with the XML output method, or whether the parameter is ignored, or whether it is validated and then ignored.

XML Output Method: the canonical Parameter

The canonical parameter specifies whether the XML output should be normalized to its canonical form, as specified by . The default value is false.

If the value is false this parameter has no effect on the output.

If the value is true then all parameters except the following are ignored: normalization-form and media-type.

The serializer MUST serialize the normalized sequence according to the rules specified at , with the octet stream created by the encoding phase of serialization () as the first parameter, and the second parameter (whether comments should be included) set to true. If comments are not desired, they should be removed before serialization.

specifies a number of changes to the serialized output that are not otherwise discussed in these specifications, such as converting each empty element to a start-end tag pair, normalizing whitespace in start and end tags, serializing namespace axes before attribute axes, sorting namespace and attribute axes lexicographically, and dropping superfluous namespace declarations. Implementations MUST raise an error on documents containing relative namespace URIs, or on octet streams that do not contain a well-formed XML document.

A serialization error results if any error is raised during the canonicalization process.

XML Output Method: the version Parameter

The version parameter specifies the version of XML and the version of Namespaces in XML to be used in the serialized output. The default value is 1.0. The version output in the XML declaration (if an XML declaration is not omitted) MUST correspond to the version of XML used by the serializer. The value of the version parameter MUST match the VersionNum production of the XML Recommendation or . A serialization error results if the value of the version parameter specifies a version of XML that is not supported by the serializer; the serializer MUST raise the error.

This document provides the normative definition of serialization for the XML output method if the version parameter has either the value 1.0 or 1.1. For any other value of version parameter, the behavior is implementation-defined. In that case the implementation-defined behavior MAY supersede all other requirements of this recommendation.

If an implementation supports a value of the version parameter for the XML or XHTML output method for which this document does not provide a normative definition, the behavior is implementation-defined.

If the serialized result would contain an NCName that contains a character that is not permitted by the version of Namespaces in XML specified by the version parameter, a serialization error results. The serializer MUST raise the error.

If the serialized result would contain a character that is not permitted by the version of XML specified by the version parameter, a serialization error results. The serializer MUST raise the error.

For example, if the version parameter has the value 1.0, and the contains a non-whitespace control character in the range U+0001 through U+001F, a serialization error results. If the version parameter has the value 1.1 and a comment node in the contains a non-whitespace control character in the range U+0001 through U+001F or a control character other than U+0085 in the range U+007F through U+009F, a serialization error results.

XML Output Method: the encoding Parameter

The encoding parameter specifies the encoding to be used in the serialized output. Serializers are REQUIRED to support values of UTF-8 and UTF-16. A serialization error occurs if an output encoding other than UTF-8 or UTF-16 is requested and the serializer does not support that encoding. The serializer MUST raise the error, or recover by using UTF-8 or UTF-16 instead. The serializer MUST NOT use an encoding whose name does not match the EncName production of the XML Recommendation .

When outputting a newline character in the , the serializer is free to represent it using any character sequence that will be normalized to a newline character by an XML parser, unless a specific mapping for the newline character is provided in a character map (see ).

When outputting any other character that is defined in the selected encoding, the character MUST be output using the correct representation of that character in the selected encoding.

It is possible that the will contain a character that cannot be represented in the encoding that the serializer is using for output. In this case, if the character occurs in a context where XML recognizes character references (that is, in the value of an attribute node or text node), then the character MUST be output as a character reference. A serialization error occurs if such a character appears in a context where character references are not allowed (for example, if the character occurs in the name of an element). The serializer MUST raise the error.

For example, if a text node contains the character U+00E9, and the value of the encoding parameter is US-ASCII, the character MUST be serialized as a character reference. If a comment node contains the same character, a serialization error results.

XML Output Method: the indent and suppress-indentation Parameters

The indent and suppress-indentation parameters control whether the serializer MAY adjust the whitespace in the serialized result so that a person will find it easier to read. If the indent parameter has the value true, the serializer MAY output whitespace characters in addition to the whitespace characters in the . It MAY also elide from the output whitespace characters that occurred in the or replace such whitespace characters with other whitespace characters.

The term content has the same meaning as the term defined in of . The immediate content of an element is the part of the content of the element that is not also in the content of a child element of that element.

If the indent parameter has the value false, the serializer MUST NOT add, elide or replace whitespace characters in the output. If the indent parameter has the value true, the serializer MUST use an algorithm for dealing with whitespace characters that satisfies all of the following constraints. If more than one constraint applies, the serializer MUST apply the most restrictive constraint. That is, if any applicable constraint indicates that whitespace MUST NOT be added, elided or replaced, that constraint prevails; if an applicable constraint indicates that whitespace SHOULD NOT be added, elided or replaced, while all other applicable constraints indicate that whitespace MAY be added, elided or replaced, whitespace SHOULD NOT be added, elided or replaced.

Whitespace characters MAY be added adjacent to a text node only if the text node contains only whitespace characters. Whitespace characters in such a text node MAY also be elided or replaced. For example, a tab MAY be inserted as a replacement for existing spaces.

Whitespace characters MAY be added, elided or replaced in the immediate content of an element whose type annotation is xs:untyped or xs:anyType and that has element node children, in the immediate content of an element whose content model is element only, or outside the content of any element.

Whitespace characters MUST NOT be added, elided or replaced in the immediate content of an element whose content model is known to be simple or empty.

Whitespace characters SHOULD NOT be added, elided or replaced in places where the characters would constitute significant whitespace, for example, in the immediate content of an element that is annotated with a type other than xs:untyped or xs:anyType, and whose content model is known to be mixed.

Whitespace characters MUST NOT be added, elided or replaced in the content of an element whose expanded QName is a member of the list of expanded QNames in the value of the suppress-indentation parameter.

Whitespace characters MUST NOT be added, elided or replaced in a part of the result document that is controlled by an xml:space attribute with value preserve. (See for more information about the xml:space attribute.)

The effect of these rules is to ensure that whitespace is added in only those places where (a) XSLT’s <xsl:strip-space> declaration could cause it to be removed, and (b) it does not affect the string value of any element node with simple content. It is usually not safe to indent document types that include elements with mixed content.

The whitespace added may possibly be based on whitespace stripped from either the source document or the stylesheet (in the case of XSLT), or guided by other means that might depend on the host language, in the case of an created using some other process.

XML Output Method: the cdata-section-elements Parameter

The cdata-section-elements parameter contains a list of expanded QNames. If the expanded QName of the parent of a text node is a member of the list, then the text node MUST be output as a CDATA section, except in those circumstances described below.

If the text node contains the sequence of characters ]]>, then the currently open CDATA section MUST be closed following the ]] and a new CDATA section opened before the >.

If the text node contains characters that are not representable in the character encoding being used in the serialized output, then the currently open CDATA section MUST be closed before such characters, the characters MUST be output using character references or entity references, and a new CDATA section MUST be opened for any further characters in the text node.

CDATA sections MUST NOT be used except where they have been explicitly requested by the user, either by using the cdata-section-elements parameter, or by using some other implementation-defined mechanism.

This is phrased to permit an implementer to provide an option that attempts to preserve CDATA sections present in the source document.

A serializer MAY provide an implementation-defined mechanism to place CDATA sections in the result tree.

XML Output Method: the omit-xml-declaration and standalone Parameters

The XML output method MUST output an XML declaration if the omit-xml-declaration parameter has the value false. The XML declaration MUST include both version information and an encoding declaration. If the standalone parameter has the value true or false, the XML declaration MUST include a standalone document declaration with the value of the standalone parameter set accordingly to yes or no. If the standalone parameter has the value omit, the XML declaration MUST NOT include a standalone document declaration; this ensures that it is both an XML declaration (allowed at the beginning of a document entity) and a text declaration (allowed at the beginning of an external general parsed entity).

A serialization error results if the omit-xml-declaration parameter has the value true, and

the standalone parameter has a value other than omit; or

the version parameter has a value other than 1.0 and the doctype-system parameter is specified.

The serializer MUST raise the error.

Otherwise, if the omit-xml-declaration parameter has the true, the XML output method MUST NOT output an XML declaration.

XML Output Method: the doctype-system and doctype-public Parameters

If the doctype-system parameter is specified, the XML output method MUST output a document type declaration immediately before the first element. The name following <!DOCTYPE MUST be the name of the first element, if any. If the doctype-public parameter is also specified, then the XML output method MUST output PUBLIC followed by the public identifier and then the system identifier; otherwise, it MUST output SYSTEM followed by the system identifier. The internal subset MUST be empty. The doctype-public parameter MUST be ignored unless the doctype-system parameter is specified.

XML Output Method: the undeclare-prefixes Parameter

The Data Model allows an element node that binds a non-empty prefix to have a child element node that does not bind that same prefix. In Namespaces in XML 1.1 (), this can be represented accurately by undeclaring prefixes. For the undeclaring prefix of the child element node, if the undeclare-prefixes parameter has the value true, the output method is XML or XHTML, and the version parameter value is greater than 1.0, the serializer MUST undeclare its namespace. If the undeclare-prefixes parameter has the value false and the output method is XML or XHTML, then the undeclaration of prefixes MUST NOT occur.

Consider an element x:foo with four in-scope namespaces that associate prefixes with URIs as follows:

x is associated with http://example.org/x

y is associated with http://example.org/y

z is associated with http://example.org/z

xml is associated with http://www.w3.org/XML/1998/namespace

Suppose that it has a child element x:bar with three in-scope namespaces:

x is associated with http://example.org/x

y is associated with http://example.org/y

xml is associated with http://www.w3.org/XML/1998/namespace

If namespace undeclaration is in effect, it will be serialized this way:

<x:foo xmlns:x="http://example.org/x" xmlns:y="http://example.org/y" xmlns:z="http://example.org/z"> <x:bar xmlns:z="">...</x:bar> </x:foo>

In Namespaces in XML 1.0 (), prefix undeclaration is not possible. If the output method is XML or XHTML, the value of the undeclare-prefixes parameter is true, and the value of the version parameter is 1.0, a serialization error results; the serializer MUST raise the error.

XML Output Method: the normalization-form Parameter

The normalization-form parameter is applicable to the XML output method. The values NFC and none MUST be supported by the serializer. A serialization error results if the value of the normalization-form parameter specifies a normalization form that is not supported by the serializer; the serializer MUST raise the error.

The meanings associated with the possible values of the normalization-form parameter are as follows:

NFC specifies the serialized result will be in Normalization Form C, using the rules specified in .

NFD specifies the serialized result will be in Normalization Form D, as specified in .

NFKC specifies the serialized result will be in Normalization Form KC, as specified in .

NFKD specifies the serialized result will be in Normalization Form KD, as specified in .

fully-normalized specifies the serialized result will be in fully normalized text, as specified in .

none specifies that no Unicode Normalization will be applied.

An implementation-defined value has an implementation-defined effect.

If the value of the normalization-form form parameter is not NFC, NFD, NFKC, NFKD, fully-normalized, or none then the meaning of the value and its effect is implementation-defined.

If the value of the parameter is fully-normalized, then no relevant construct of the parsed entity created by the serializer may start with a composing character. The term relevant construct has the meaning defined in section 2.13 of . If this condition is not satisfied, a serialization error MUST be raised.

Specifying fully-normalized as the value of this parameter does not guarantee that the XML document output by the serializer will in fact be fully normalized as defined in . This is because the serializer does not check that the text is include normalized, which would involve checking all external entities that it refers to (such as an external DTD). Furthermore, the serializer does not check whether any character escape generated using character maps represents a composing character.

XML Output Method: the media-type Parameter

The media-type parameter is applicable to the XML output method. See for more information.

XML Output Method: the use-character-maps Parameter

The use-character-maps parameter is applicable to the XML output method. The result of serialization using the XML output method is not guaranteed to be well-formed XML if character maps have been specified. See for more information.

XML Output Method: the byte-order-mark Parameter

The byte-order-mark parameter is applicable to the XML output method. See for more information.

The byte order mark may be undesirable under certain circumstances, for example, to concatenate resulting XML fragments without additional processing to remove the byte order mark. Therefore this specification does not mandate the byte-order-mark parameter to have the value true when the encoding is UTF-16, even though the XML 1.0 and XML 1.1 specifications state that entities encoded in UTF-16 MUST begin with a byte order mark. Consequently, this specification does not guarantee that the resulting XML fragment, without a byte order mark, will not cause an error when processed by a conforming XML processor.

XML Output Method: the item-separator Parameter

The effect of the item-separator serialization parameter is described in .

XHTML Output MethodIn the HTML and XHTML output methods, the rules for adding and replacing meta elements have been revised to take account of the new HTML5 syntax, for example <meta charset="UTF-8">. The default HTML version is now 5. This may result in changes to the serialized output in cases where no explicit HTML version is requested.

The XHTML output method serializes the as XML, using the HTML compatibility guidelines defined in the XHTML specification ( or the XHTML syntax of HTML5 (see ).

The default value of the html-version serialization parameter for this method is 5.0, and all references to the value of this parameter assume this default when the parameter is absent. The value of the parameter is a decimal, so the values 5 and 5.0 are equivalent.

The term with HTML5 is used in this specification to qualify rules that apply only when the effective version of the html-version serialization parameter is 5.0.

The term prior to HTML5 is used in this specification to qualify rules that apply only when the effective version of the html-version serialization parameter is less than 5.0.

An element node is recognized as an HTML element by the XHTML output method if either of the following conditions is true:

the element node is in the XHTML namespace; or

With HTML5: the element has a null namespace URI and the local part of the name is equal to the name of an element defined by HTML5 , making the comparison without regard to case.

It is entirely the responsibility of the supplier of the to ensure that it conforms to the relevant specification, this being:

With HTML5, the XHTML syntax of HTML5;

Prior to HTML5, the or specification.

It is not an error if the is invalid XHTML. Equally, it is entirely under the control of the supplier of the whether the output conforms to XHTML 1.0 Strict, XHTML 1.0 Transitional, the XHTML syntax of HTML5 (see ), or any other specific definition of XHTML.

The serialization of the follows the same rules as for the XML output method, with the general exceptions noted below and parameter-specific exceptions in . These differences are based on the HTML compatibility guidelines published in Appendix C of and on , both of which are designed to ensure that as far as possible, XHTML is rendered correctly on user agents designed originally to handle HTML.

With HTML5 the is first subjected to prefix normalization.

During prefix normalization, any element node in the that is in one of the XHTML namespace, the SVG namespace or the MathML namespace has its name replaced by the local part of its name. Such an element node is given a default namespace node whose value is the element’s namespace URI. Any namespace node for any of those three namespaces that was previously present on any element node in the is also removed, unless the prefix that that namespace node declared is used as the prefix on the name of an attribute on that element or an ancestor of that element.

The process of prefix normalization is equivalent to replacing the with the result of the transformation described by this XSLT stylesheet, with the root of the as the initial context value.

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="4.0" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mathml="http://www.w3.org/1998/Math/MathML"> <xsl:template match="xhtml:*|svg:*|mathml:*"> <xsl:element name="{local-name()}" namespace="{namespace-uri()}"> <xsl:apply-templates select="@*|namespace::*|node()"/> </xsl:element> </xsl:template> <xsl:template match="node()|@*|namespace::*"> <xsl:copy copy-namespaces="no"> <xsl:apply-templates select="@*|namespace::*|node()"/> </xsl:copy> </xsl:template> <xsl:template match="namespace::*[. eq 'http://www.w3.org/1999/xhtml']| namespace::*[. eq 'http://www.w3.org/2000/svg']| namespace::*[. eq 'http://www.w3.org/1998/Math/MathML']"/> </xsl:stylesheet>

The following XHTML elements have an EMPTY content model: area, base, br, col, embed, hr, img, input, link, meta, basefont, frame, isindex, and param. The void elements of HTML5 are area, base, br, col, embed, hr, img, input, keygen, link, meta, param, source, track and wbr.

An element node is expected to be empty if it is recognized as an HTML element and:

With HTML5, the element is a void element.

Prior to HTML5, the content model is EMPTY.

If an element node that has no child nodes is not expected to be empty, and:

With HTML5, the HTML element is not a void element, or

Prior to HTML5, the content model of the HTML element is not EMPTY (for example, an empty title or paragraph)

then the serializer MUST NOT use the minimized form. That is, it MUST output <p></p> and not <p />.

If an element that has no children is expected to be empty, the serializer MUST use the minimized tag syntax, for example <br />, as the alternative syntax <br></br> allowed by XML gives uncertain results in many legacy user agents. If the html-version serialization parameter has a value less than 5.0, the serializer MUST include a space before the trailing />, e.g. <br />, <hr /> and <img src="karen.jpg" alt="Karen" />.

Prior to HTML5, the serializer MUST NOT use the entity reference ' which, although defined in XML and therefore in XHTML, is not defined in versions of HTML prior to HTML5, and is not recognized by all HTML user agents.

With HTML5, the serializer SHOULD output namespace declarations in a way that is consistent with the requirements of .

Prior to HTML5, the serializer SHOULD output namespace declarations in a way that is consistent with the requirements of the XHTML DTD if this is possible.

The XHTML 1.0 DTDs require the declaration xmlns="http://www.w3.org/1999/xhtml" to appear on the html element, and only on the html element. The specification permits namespace declarations to appear in a conforming document, but restricts the elements on which they can appear. The serializer MUST output namespace declarations that are consistent with the namespace nodes present in the result tree, but it MUST avoid outputting redundant namespace declarations on elements where the DTD would make them invalid, for versions prior to HTML5, or where they are not permitted by , for serialization according to the syntax of HTML5.

If the html element is generated by an XSLT literal result element of the form <html xmlns="http://www.w3.org/1999/xhtml"> ... </html>, or by an XQuery direct element constructor of the same form, then the html element in the result document will have a node name whose prefix is "", which will satisfy the requirements of the DTD. In other cases the prefix assigned to the element is implementation-dependent.

and Appendix C of describe a number of compatibility guidelines for users of XHTML who wish to render their XHTML documents with HTML user agents. In some cases, such as the guideline on the form empty elements take, only the serialization process itself has the ability to follow the guideline. In such cases, those guidelines are reflected in the requirements on the serializer described above.

In all other cases, the guidelines can be adhered to by the . The guideline on the use of whitespace characters in attribute values is one such example. Another example is that xml:lang="..." does not serialize to both xml:lang="..." and lang="..." as required by some legacy user agents. It is the responsibility of the person or process that creates the instance of the data model that is input to the serialization process to ensure it is created in a way that is consistent with the guidelines. No serialization error results if the does not adhere to the guidelines.

The Influence of Serialization Parameters upon the XHTML Output Method

The serialization parameters that affect the XHTML output method are listed in the following subsections.

Serialization parameters other than those listed are not applicable to this output method. It is the responsibility of the host language to specify whether an error occurs if such a parameter is specified in combination with the XHTML output method, or whether the parameter is ignored, or whether it is validated and then ignored.

XHTML Output Method: the canonical Parameter

The canonical parameter specifies whether the XHTML output should be normalized to its canonical form, as specified by . The default value is false.

If the value is false this parameter has no effect on the output.

If the value is true then all parameters except the following are ignored: normalization-form, html-version, media-type, and include-content-type.

A serialization error results if any error is raised during the canonicalization process.

XHTML Output Method: the version Parameter

The behavior for the version parameter for the XHTML output method is described in . Note that this affects the version of XML used, not the version of HTML.

XHTML Output Method: the html-version Parameter

The html-version parameter specifies whether the XHTML output method will produce a serialized document following rules that are tailored to the requirements of the XHTML syntax of , or to the requirements of and .

The differences are described in detail throughout .

XHTML Output Method: the encoding Parameter

The behavior for encoding parameter for the XHTML output method is described in .

XHTML Output Method: the indent and suppress-indentation Parameters

If the indent parameter has the value true, the serializer MAY add or remove whitespace as it serializes the result tree, if it observes the following constraints.

Whitespace MUST NOT be added other than before or after an element, or adjacent to an existing whitespace character.

Whitespace MUST NOT be added or removed adjacent to an inline element. The inline elements are those elements recognized as HTML elements that are in the %inline category of any of the XHTML 1.0 DTDs, in the %inline.class category of the XHTML 1.1 DTD, those elements defined to be phrasing elements in HTML5 and elements recognized as HTML elements with local names ins and del if they are used as inline elements (i.e., if they do not contain element children).

Whitespace MUST NOT be added or removed inside a formatted element, the formatted elements being those recognized as HTML elements with local names pre, script, style, title, and textarea.

Whitespace characters MUST NOT be added in the content of an element whose expanded QName matches a member of the list of expanded QNames in the value of the suppress-indentation parameter. The expanded QName of an element node is considered to match a member of the list of expanded QNames if:

the two expanded QNames are equal; or

the expanded QNames both have null namespace URIs, and the local parts of the two QNames are equal without regard to case; or

the value of the html-version serialization parameter is 5.0, the local parts of the two QNames are equal without regard to case and one QName has a null namespace URI and the namespace URI of the other is equal to the XHTML namespace URI.

The effect of the above constraints is to ensure any insertion or deletion of whitespace would not affect how an HTML user agent that conforms to the specified version of HTML would render the output, assuming the serialized document does not refer to any HTML style sheets.

The HTML definition of whitespace is different from the XML definition: see section 9.1 of 4.01 specification.

XHTML Output Method: the cdata-section-elements Parameter

The behavior for cdata-section-elements parameter for the XHTML output method is described in .

XHTML Output Method: the omit-xml-declaration and standalone Parameters

The behavior for omit-xml-declaration and standalone parameters for the XHTML output method is described in .

As with the XML output method, the XHTML output method specifies that an XML declaration will be output unless it is suppressed using the omit-xml-declaration parameter. Appendix C.1 of provides advice on the consequences of including, or omitting, the XML declaration.

XHTML Output Method: the doctype-system and doctype-public Parameters

With HTML5, if the doctype-system serialization parameter is absent, the first element node child of the document node that is to be serialized is recognized as an HTML element, the local part of the QName of which is equal to the string HTML, without regard to case, and any text node preceding that element in document order contains only whitespace characters, then the XHTML output method MUST output a document type declaration immediately before the first element, with no public or system identifier. The name following <!DOCTYPE MUST be the same as the local part of the name of the element.

Otherwise, the behavior for doctype-system and doctype-public parameters for the XHTML output method is described in .

XHTML Output Method: the undeclare-prefixes Parameter

The behavior for undeclare-prefixes parameter for the XHTML output method is described in .

XHTML Output Method: the normalization-form Parameter

The behavior for normalization-form parameter for the XHTML output method is described in .

XHTML Output Method: the media-type Parameter

The behavior for media-type parameter for the XHTML output method is described in .

XHTML Output Method: the use-character-maps Parameter

The behavior for use-character-maps parameter for the XHTML output method is described in .

XHTML Output Method: the byte-order-mark Parameter

The behavior for byte-order-mark parameter for the XHTML output method is described in .

XHTML Output Method: the escape-uri-attributes Parameter

If the escape-uri-attributes parameter has the value true, the XHTML output method MUST apply URI escaping to URI attribute values, except that relative URIs MUST NOT be absolutized.

This escaping is deliberately confined to non-ASCII characters, because escaping of ASCII characters is not always appropriate, for example when URIs or URI fragments are interpreted locally by the HTML user agent. Even in the case of non-ASCII characters, escaping can sometimes cause problems. More precise control of URI escaping is therefore available by setting escape-uri-attributes to false, and controlling the escaping of URIs by using methods defined in and .

XHTML Output Method: the include-content-type Parameter

If the includes a head element recognized as an HTML element, and the include-content-type parameter has the value true, the XHTML output method MUST add a meta element as the first child element of the head element, specifying the character encoding actually used. The meta element SHOULD be in no namespace if the head element is in no namespace, and in the XHTML namespace if the head element is in the XHTML namespace.

Prior to HTML5, the generated meta element MUST take the form shown below (assuming encoding EUC-JP):

<head> <meta http-equiv="Content-Type" content="text/html; charset=EUC-JP" /> ...

With HTML5, the generated meta element MUST take the form shown below (again assuming encoding EUC-JP):

<head> <meta charset="EUC-JP"/> ...

The content type, when included, SHOULD be set to the value given for the media-type parameter.

It is recommended that the host language use as default value for this parameter one of the MIME types () registered for XHTML. Currently, these are text/html (registered by ) and application/xhtml+xml (registered by ). Note that some user agents fail to recognize the charset parameter if the content type is not text/html.

If a meta element has been added to the head element as described above, then any existing meta element child of the head element having either a charset attribute, or an http-equiv attribute with the value "Content-Type", making the comparison without regard to case after first stripping leading and trailing spaces from the value of the attribute solely for the purposes of comparison, MUST be discarded.

This process removes possible parameters in the attribute value. For example,

in the might be replaced by

The effect of the item-separator serialization parameter is described in .

HTML Output MethodIn the HTML and XHTML output methods, the rules for adding and replacing meta elements have been revised to take account of the new HTML5 syntax, for example <meta charset="UTF-8">.The default HTML version is now 5. This may result in changes to the serialized output in cases where no explicit HTML version is requested.

The HTML output method serializes the as HTML.

For example, the following XSL stylesheet generates html output,

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" version="4.0"/> <xsl:template match="/"> <html> <xsl:apply-templates/> </html> </xsl:template> ... </xsl:stylesheet>

In the example, the version attribute of the xsl:output element indicates the version of the HTML Recommendation to which the serialized result is to conform.

The requested HTML version is the value of the html-version serialization parameter if present; otherwise the value of the version serialization parameter if present; otherwise 5.0.

This document provides the normative definition of serialization for the HTML output method if the requested HTML version has the lexical form of a value of type decimal whose value is 1.0 or greater, but no greater than 5.0. For any other requested HTML version, the behavior is implementation-defined. In that case the implementation-defined behavior MAY supersede all other requirements of this recommendation.

If an implementation supports a value of the version parameter for the HTML output method for which this document does not provide a normative definition, the behavior is implementation-defined.

An implementation is required to behave as specified in this document when the requested version is 5.0. If the requested version is greater than or equal to 1 but less than 5.0, then the processor may behave as if the requested version were 5.0.

It is entirely the responsibility of the supplier of the to ensure that it conforms to the relevant HTML specification. It is not an error if the is invalid HTML. Equally, it is entirely under the control of the supplier of the whether the output conforms to HTML. If the result tree is valid HTML, the serializer MUST serialize the result in a way that conforms with the requested HTML version.

Markup for Elements

As described in detail below, the HTML output method will not output an element differently from the XML output method unless the element is to be serialized as an HTML element.

The portion of the serialized document representing the result of serializing an element that is not to be serialized as an HTML element is known as an XML Island.

An element node is serialized as an HTML element if

the expanded QName of the element has a null namespace URI, or

the requested HTML version is 5.0 or greater, and the element node is in the XHTML namespace.

If the element is to be serialized as an HTML element, but the local part of the expanded QName is not recognized as the name of an HTML element, the element MUST be output in the same way as a non-empty, inline element such as span. In particular:

Any namespace node in the result tree for the XML namespace is ignored by the HTML output method. In addition, if the requested HTML version is 5.0, any element node that has a prefix and is in the XHTML namespace, MathML namespace, or SVG namespace MUST be serialized with an unprefixed element name. The serializer MUST serialize an attribute with the name xmlns whose value is equal to the namespace URI of the element node, unless an ancestor element in the serialized result already has an attribute named xmlns with the same value, and no intervening element has an attribute named xmlns with a different value. If the element node has a namespace node for the default namespace whose value is not equal to the namespace URI of the element node, the namespace node is ignored. The serializer MUST NOT serialize a namespace declaration for the namespace node declaring the element node’s prefix, unless an attribute of the element node has the same prefix. For namespace nodes in the result tree that are not ignored, the HTML output method MUST represent these namespaces using attributes named xmlns or xmlns:prefix in the same way as the XML output method would represent them when the version parameter is set to 1.0.

If the result tree contains elements or attributes whose names have a non-null namespace URI, the HTML output method MUST generate namespace-prefixed QNames for these nodes in the same way as the XML output method would do when the version parameter is set to 1.0.

Where special rules are defined later in this section for serializing specific HTML elements and attributes, these rules MUST NOT be applied to an element that is not to be serialized as an HTML element or an attribute whose name has a non-null namespace URI. However, the generic rules for the HTML output method that apply to all elements and attributes, for example the rules for escaping special characters in the text and the rules for indentation, MUST be used also for namespaced elements and attributes.

When serializing an element whose name is not defined in the HTML specification, but that is to be serialized as an HTML element, the HTML output method MUST apply the same rules (for example, indentation rules) as when serializing a span element. The descendants of such an element MUST be serialized as if they were descendants of a span element.

When serializing an element whose name is in a non-null namespace, the HTML output method MUST apply the same rules (for example, indentation rules) as when serializing a div element. The descendants of such an element MUST be serialized as if they were descendants of a div element, except for the influence of the cdata-section-elements serialization parameter on any text node children of the element.

The HTML output method MUST NOT output an end-tag for an empty element if the element type has an empty content model, and the value of the requested HTML version is less than 5.0, or the element is a void element and the value of the requested HTML version is 5.0. For example, an element written as <br/> or <br></br> in an XSLT stylesheet MUST be output as <br>.

For HTML 4.0, the element types that have an empty content model are area, base, basefont, br, col, embed, frame, hr, img, input, isindex, link, meta and param. For HTML5, the void elements are area, base, br, col, embed, hr, img, input, keygen, link, meta, param, source, track and wbr. It is implementation-defined whether the basefont, frame and isindex elements, which are not part of HTML5, are considered to be void elements when the requested HTML version has the value 5.0.

For the HTML output method, it is implementation-defined whether the basefont, frame and isindex elements, which are not part of HTML5, are considered to be void elements when the requested HTML version has the value 5.0.

The markup generation step of the phases of serialization only creates start tags and end tags for the HTML output method, never XML-style empty element tags. As such, a serializer MUST serialize an HTML element that has no children, but whose content model is not empty, using a pair of adjacent start and end element tags, or as a solitary start tag if permitted by the context.

For any element node that is to be serialized as an HTML element, the HTML output method MUST compare the local part of the name of the element node with the names of HTML elements, making the comparison without regard to case. If the local part of the name of the element node compares equal to that of any HTML element, the element node MUST be recognized as being that kind of HTML element. For example, elements named br, BR or Br MUST all be recognized as the HTML br element and output without an end tag.

The HTML output method MUST NOT perform escaping for any text node descendant, nor for any attribute of an element node descendant, of a script or style element.

For example, a script element created by an XQuery direct element constructor or an XSLT literal result element, such as:

MUST be output as

A common requirement is to output a script element as shown in the example below:

This is invalid HTML, for the reasons explained in section B.3.2 of the 4.01 specification. Nevertheless, it is possible to output this fragment using either of the following constructs:

Firstly, by use of a script element created by an XQuery direct element constructor or an XSLT literal result element:

Secondly, by constructing the markup from ordinary text characters:

As the specification points out, the correct way to write this is to use the escape conventions for the specific scripting language. For JavaScript, it can be written as:

The 4.01 specification also shows examples of how to write this in various other scripting languages. The escaping MUST be done explicitly; it will not be done by the serializer.

Writing Attributes

The HTML output method MUST NOT escape "<" characters occurring in attribute values.

A boolean attribute is an attribute with only a single allowed value in any of the HTML DTDs or that is specified to be a boolean attribute by HTML5 (see ), where the allowed value is equal without regard to case to the name of the attribute. The HTML output method MUST output any boolean attribute in minimized form if and only if the value of the attribute node actually is equal to the name of the attribute making the comparison without regard to case.

For example, a start-tag created using the following XQuery direct element constructor or XSLT literal result element

MUST be output as

The HTML output method MUST NOT escape a & character occurring in an attribute value immediately followed by a { character (see Section B.7.1 of the HTML Recommendation ).

For example, a start-tag created using the following XQuery direct element constructor or XSLT literal result element

MUST be output as

See for additional directives on how attributes MAY be written.

Writing Character Data

The HTML output method MAY output a character using a character entity reference in preference to using a numeric character reference, if an entity is defined for the character in the version of HTML that the output method is using. Entity references and character references SHOULD be used only where the character is not present in the selected encoding, or where the visual representation of the character is unclear (as with  , for example).

When outputting a sequence of whitespace characters in the , within an element where whitespace characters are treated normally (but not in elements such as pre and textarea), the HTML output method MAY represent it using any sequence of whitespace characters that will be treated in the same way by an HTML user agent. See section 3.5 of for some additional information on handling of whitespace by an HTML user agent for versions of HTML prior to HTML5, and see for information on the handling of whitespace characters by an HTML5 user agent.

The terms space character and whitespace character defined in HTML5 do not match the definition of whitespace character in this specification.

Certain characters are permitted in XML, but not in HTML prior to HTML5 — for example, the control characters U+007F through U+009F are permitted in both XML 1.0 and XML 1.1, and the control characters U+0001 through U+0008, U+000B, U+000C and U+000E through U+001F are permitted in XML 1.1, but none of these is permitted in HTML prior to HTML5. It is a serialization error to use the HTML output method if such characters appear in the and the value of the requested HTML version is less than 5.0. The serializer MUST raise the error.

Writing Comments and Processing InstructionsThe way processing instructions are handled when generating HTML5 has changed, reflecting the fact that HTML5 no longer recognizes processing instructions.

Comment nodes are written as HTML comments, using the syntax .

Prior to HTML5, the HTML output method MUST terminate processing instructions with > rather than ?>. It is a serialization error to use the HTML output method when > appears within a processing instruction in .

With HTML5, a processing instruction MUST be written as an HTML comment, in the form . Here target is the name of the processing instruction, and data is its string value; they are separated by a single space. If the string value of the processing instruction contains two adjacent hyphens, they MUST be separated in the output by a single space. The space separator is omitted if the string value of the processing instruction is zero-length. For example, the processing instruction <?xml-stylesheet type="text/xsl" href="render.xsl"?> is serialized as <--?xml-stylesheet type="text/xsl" href="render.xsl"?-->

The Influence of Serialization Parameters upon the HTML Output Method

The serialization parameters that affect the HTML output method are listed in the following subsections.

Serialization parameters other than those listed are not applicable to this output method. It is the responsibility of the host language to specify whether an error occurs if such a parameter is specified in combination with the HTML output method, or whether the parameter is ignored, or whether it is validated and then ignored.

HTML Output Method: the version and html-version Parameters

These two parameters are used to determine the .

HTML Output Method: the encoding Parameter

The encoding parameter specifies the encoding to be used. Serializers are REQUIRED to support values of UTF-8 and UTF-16. A serialization error occurs if an output encoding other than UTF-8 or UTF-16 is requested and the serializer does not support that encoding. The serializer MUST raise the error.

It is possible that the will contain a character that cannot be represented in the encoding that the serializer is using for output. In this case, if the character occurs in a context where HTML recognizes character references, then the character MUST be output as a character entity reference or decimal numeric character reference; otherwise (for example, in a script or style element or in a comment), the serializer MUST raise a serialization error .

See regarding how this parameter is used with the include-content-type parameter.

HTML Output Method: the indent and suppress-indentation Parameters

If the indent parameter has the value true, then the HTML output method MAY add or remove whitespace as it serializes the result tree, if it observes the following constraints.

Whitespace MUST NOT be added other than before or after an element, or adjacent to an existing whitespace character.

Whitespace MUST NOT be added or removed adjacent to an inline element. The inline elements are:

Prior to HTML5: elements included in the %inline category of any of the HTML 4.01 DTDs

With HTML5: elements defined to be phrasing elements in HTML5

as well as the ins and del elements if they do not contain element children.

Whitespace MUST NOT be added or removed inside a formatted element, the formatted elements being pre, script, style, title, and textarea.

the two expanded QNames are equal;

the expanded QNames both have null namespace URIs, and the local parts of the two QNames are equal without regard to case; or

the value of the requested HTML version is 5.0, the local parts of the two QNames are equal without regard to case and one QName has a null namespace URI and the namespace URI of the other is equal to the XHTML namespace URI.

The effect of the above constraints is to ensure that any insertion or deletion of whitespace would not affect how a conforming HTML user agent would render the output, assuming the serialized document does not refer to any HTML style sheets.

Note that the HTML definition of whitespace is different from the XML definition (see section 9.1 of the specification).

HTML Output Method: the cdata-section-elements Parameter

The cdata-section-elements parameter is not applicable to the HTML output method, except in the case of XML Islands.

HTML Output Method: the doctype-system and doctype-public Parameters

If the doctype-public or doctype-system parameters are specified, then the HTML output method MUST output a document type declaration. If the doctype-public parameter is specified, then the output method MUST output PUBLIC followed by the specified public identifier; if the doctype-system parameter is also specified, it MUST also output the specified system identifier following the public identifier. If the doctype-system parameter is specified but the doctype-public parameter is not specified, then the output method MUST output SYSTEM followed by the specified system identifier.

If the value of the requested HTML version is 5.0, the doctype-public and doctype-system serialization parameters are both absent, the first element node child of the document node that is to be serialized is to be serialized as an HTML element, the local part of the QName of which is equal to the string HTML, without regard to case, and any text node that precedes that element node in the document contains only whitespace characters, then the HTML output method MUST output a document type declaration, with no public or system identifier.

If the HTML output method MUST output a document type declaration, it MUST be serialized immediately before the first element, if any, and the name following <!DOCTYPE MUST be HTML or html.

HTML Output Method: the normalization-form Parameter

The normalization-form parameter is applicable to the HTML output method. The values NFC and none MUST be supported by the serializer. A serialization error results if the value of the normalization-form parameter specifies a normalization form that is not supported by the serializer; the serializer MUST raise the error.

HTML Output Method: the media-type Parameter

The media-type parameter is applicable to the HTML output method. See for more information. See regarding how this parameter is used with the include-content-type parameter.

HTML Output Method: the use-character-maps Parameter

The use-character-maps parameter is applicable to the HTML output method. See for more information.

HTML Output Method: the byte-order-mark Parameter

The byte-order-mark parameter is applicable to the HTML output method. See for more information.

HTML Output Method: the escape-uri-attributes Parameter

If the escape-uri-attributes parameter has the value true, the HTML output method MUST apply URI escaping to URI attribute values, except that relative URIs MUST NOT be absolutized.

HTML Output Method: the include-content-type Parameter

If there is a head element, and the include-content-type parameter has the value true, the HTML output method MUST add a meta element as the first child element of the head element specifying the character encoding actually used.

Prior to HTML5, the generated meta element MUST take the form shown below (assuming encoding EUC-JP):

<head> <meta http-equiv="Content-Type" content="text/html; charset=EUC-JP" > ...

With HTML5, the generated meta element MUST take the form shown below (again assuming encoding EUC-JP):

<head> <meta charset="EUC-JP"> ...

The content type, when included, MUST be set to the value given for the media-type parameter.

If a meta element has been added to the head element as described above, then any existing meta element child of the head element having a charset attribute or an http-equiv attribute with the value "Content-Type", making the comparison without regard to case after first stripping leading and trailing spaces from the value of the attribute solely for the purposes of comparison, MUST be discarded.

This process removes possible parameters in the attribute value. For example,

in the might be replaced by

or by

The effect of the item-separator serialization parameter is described in .

Text Output Method

The Text output method serializes the by outputting the string value of the document node created by the markup generation step of the phases of serialization without any escaping.

A newline character in the MAY be output using any character sequence that is conventionally used to represent a line ending in the chosen system environment.

The rule just stated applies to the character U+000A; it does not apply to occurrences in the of U+000D, U+0085, or U+2028: these should be output literally, regardless of the conventions for line endings in the system environment.

To illustrate, the following table shows the expected output for various character sequences in environments which conventionally use U+000A (LF, as in Linux systems), U+000D followed by U+000A (CR+LF, Windows), U+000D (CR only, older versions of Mac OS), U+0085 (some IBM operating systems), or U+2028 to separate lines:

Input	#xA systems	#xD#xA systems	#xD systems	#x85 systems	#x2028 systems
character #xD	character #xD	character #xD	character #xD	character #xD	character #xD
character #xA	character #xA	string #xD + #xA	character #xD	character #x85	character #x2028
string #xD + #xA	string #xD + #xA	string #xD + #xD + #xA	string #xD + #xD	string #xD + #x85	string #xD + #x2028
string #xD + #xD + #xA	string #xD + #xD + #xA	string #xD + #xD + #xD + #xA	string #xD + #xD + #xD	string #xD + #xD + #x85	string #xD + #xD + #x2028

The Influence of Serialization Parameters upon the Text Output Method

The serialization parameters that affect the Text output method are listed in the following subsections.

Serialization parameters other than those listed are not applicable to this output method. It is the responsibility of the host language to specify whether an error occurs if such a parameter is specified in combination with the Text output method, or whether the parameter is ignored, or whether it is validated and then ignored.

Text Output Method: the encoding Parameter

The encoding parameter identifies the encoding that the Text output method MUST use to convert sequences of characters to sequences of bytes. Serializers are REQUIRED to support values of UTF-8 and UTF-16. A serialization error occurs if the serializer does not support the encoding specified by the encoding parameter. The serializer MUST raise the error. If the contains a character that cannot be represented in the encoding that the serializer is using for output, the serializer MUST raise a serialization error .

Text Output Method: the normalization-form Parameter

The normalization-form parameter is applicable to the Text output method. The values NFC and none MUST be supported by the serializer. A serialization error results if the value of the normalization-form parameter specifies a normalization form that is not supported by the serializer; the serializer MUST raise the error.

Text Output Method: the media-type Parameter

The media-type parameter is applicable to the Text output method. See for more information.

Text Output Method: the use-character-maps Parameter

The use-character-maps parameter is applicable to the Text output method. See for more information.

Text Output Method: the byte-order-mark Parameter

The byte-order-mark parameter is applicable to the Text output method. See for more information.

Text Output Method: the item-separator Parameter

The effect of the item-separator serialization parameter is described in .

JSON Output Method Added the escape-solidus parameter for JSON serialization. Added the json-lines parameter for JSON serialization. The serialization of maps retains the order of entries. A JNode is replaced by its ·content· property. JSON canonicalization is supported by the ·canonical· property. The JSON output method now produces fallback representation of NaN and infinity, rather than reporting an error for such values.

The JSON output method serializes the using the JSON syntax defined in , or (if the json-lines parameter is set to true) the json-lines syntax defined at . Sequence normalization is not performed for this output method. The effect of the json-lines parameter is explained at .

If json-lines is set to false, then:

If the is an empty sequence, it is serialized as the string null.

If the input value is a single item, it is serialized as described below.

If the input value is a sequence containing two or more items, a serialization error results .

Serializing Items

An individual item is serialized as follows:

A JNode is serialized by serializing its ·content· property.

An array item in the is serialized to a JSON array by outputting the serialized JSON value of each member within the array separated by delimiters according to the JSON array syntax, i.e. [member, member, ...]. Each member in the array is to be serialized by recursively applying the rules in this section.

A map item in the is serialized to a JSON object by outputting, for each key/value pair, the string value of the key to a JSON string, followed by the serialized JSON value of the entry, separated by delimiters according to the JSON object syntax, i.e. {key:value, key:value, ...}. The key/value pairs in the serialized output retain the entry order of entries in the map, unless canonical is true, in which case map entries MUST be sorted according to the rules of .

These rules require sorting according to the UTF-16 representation of the string, which is not the same (in the presence of surrogate pairs) as sorting using the XPath codepoint collation.

If any two keys of the map item have the same string value, serialization error is raised, unless the allow-duplicate-names parameter is true and the canonical parameter is false.

A node in the is serialized to a JSON string by outputting the result of serializing the node using the method specified by the json-node-output-method parameter. If the value of the canonical parameter is false, the node is serialized with the serialization parameter omit-xml-declaration set to true and with no other serialization parameters set, otherwise (canonical is true) all parameters are inherited by the sub-serialization process.

An atomic value of type xs:numeric is serialized to a JSON number.

If the canonical parameter is true, then the value is cast to type xs:double and the result is serialized according to the rules of (and by extension ).

If the canonical parameter is false then:

A value of type xs:decimal (including xs:integer) is output in the format that results from casting the value to xs:string.

A value of type xs:float is first cast to type xs:double, and then output in the same way as an xs:double.

Implementations MAY serialize an xs:double value using any lexical representation of a JSON number defined in , but it is RECOMMENDED to use the same representation as when the canonical parameter is true.

The value NaN is serialized as the JSON token null.

The values positive and negative infinity are serialized as 1e9999 and -1e9999 respectively.

These values are permitted by the JSON grammar, but some JSON parsers may reject them. For interoperability, they should be avoided.

An atomic item of type xs:boolean is serialized to the JSON token true or false.

An atomic item of type xs:QName in the whose namespace part is "http://www.w3.org/2005/xpath-functions" and whose local part is "null" is serialized to the JSON token null.

This rule is introduced in 4.0, along with an option in the fn:parse-json function to allow a user-defined representation of the JSON value null. While the default representation of null as an empty sequence is usable in many circumstances, an explicit representation of null as a recognizable item can make some operations on JSON-derived values easier.

Any other atomic value in the is serialized to a JSON string by outputting the result of applying the fn:string function to the item.

An empty sequence in the is serialized to the JSON token null.

A sequence of length greater than one in the will result in a serialization error .

Any item in the of a type not specified in the above list will result in a serialization error .

Whenever a value is serialized to a JSON string, the following procedure is applied to the supplied string:

If the canonical parameter is true, then the string is output as specified in . The string is first normalized if requested using the normalization-form parameter. The serialization parameters escape-solidus and use-character-maps are ignored.

The escaping rules are restated here for convenience:

If the Unicode value falls within the traditional ASCII control character range (U+0000 through U+001F), it MUST be serialized using lowercase hexadecimal Unicode notation (\uhhhh) unless it is in the set of predefined JSON control characters U+0008, U+0009, U+000A, U+000C, or U+000D, which MUST be serialized as \b, \t, \n, \f, and \r, respectively.

If the Unicode value is outside of the ASCII control character range, it MUST be serialized “as is” unless it is equivalent to U+005C or U+0022, which MUST be serialized as \\ and \", respectively.

Note that the C1 control characters (codepoints 127-159) are not included in this list.

In canonical JSON, property values within an object are sorted based on their UTF16 representation. This corresponds to the default sort order in languages such as Javascript, Java, and C#, but in the presence of codepoints above 65535, it is not the same as the order produced by Unicode codepoint collation.

Otherwise (when canonical is false):

Any character in the string for which character mapping is defined (see ) is substituted by the replacement string defined in the character map.

Any other character in the input string (but not a character produced by character mapping) is a candidate for Unicode Normalization if requested by the normalization-form parameter, and JSON escaping. JSON escaping replaces the characters U+005C, U+0008, U+000C, U+000A, U+000D, U+0009, or U+005C by the corresponding JSON escape sequences \", \b, \f, \n, \r, \t, or \\ respectively, and any other codepoint in the range 1-31 or 127-159 by an escape in the form \uHHHH where HHHH is the hexadecimal representation of the codepoint value. Escaping further replaces the solidus character (/) by the escape sequence \/ if the escape-solidus parameter is set to true, but not if it is set to false. Escaping is also applied to any characters that cannot be represented in the selected encoding.

The resulting string is enclosed in double quotation marks.

Finally, encoding, as controlled by the encoding parameter, converts the character stream produced by the preceding rules into an octet stream. The encoding parameter is ignored if canonical is true.

JSON Lines

When the json-lines parameter is set to true, the serialized output is written in json-lines format, as defined in .

If json-lines is set to true, then each item in the is serialized indepedently as a JSON text, and the resulting serializations are then concatenated using a single U+000A character as a separator.

If json-lines and indent are both set to true, then the serialization of each individual item may include added U+0020 and U+0009 characters for formatting purposes, but it must not include U+000A or U+000D characters.

The json-lines specification allows U+000D characters to appear, and does not treat them as significant; however, they are likely to cause practical problems. For example processing such input using the XPath expression unparsed-text-lines($uri) ! parse-json() would fail. The serializer MUST NOT output any U+000D characters, either at the end of a line or elsewhere.

The json-lines specification allows a terminating U+000A character after the last line. In the interests of interoperability, however, the serializer MUST NOT output such a terminator.

If the is an empty sequence, then it is serialized as a zero-length string (rather than as the string null).

The item-separator parameter has no effect.

The Influence of Serialization Parameters upon the JSON Output Method

When nodes are serialized using the JSON output method, serialization is delegated to the output method specified by the json-node-output-method serialization parameter. The omit-xml-declaration parameter is set to true, and no other serialization parameters are passed down to the serialization method responsible for serializing the node.

The serialization parameters that affect the JSON output method are listed in the following subsections.

Serialization parameters other than those listed are not applicable to this output method. It is the responsibility of the host language to specify whether an error occurs if such a parameter is specified in combination with the JSON output method, or whether the parameter is ignored, or whether it is validated and then ignored.

JSON Output Method: the canonical Parameter

The canonical parameter specifies whether the JSON output should be normalized to its canonical form, as specified by . The default value is false.

If the value is true this imposes constraints on the representation of maps, strings, and numbers, as described in . All other parameters except normalization-form, media-type, json-lines, and json-node-output-method are ignored (except that they are passed though to any sub-serialization of contained nodes).

The serializer MUST serialize the according to .

defines the input to canonicalization as an I-JSON text . The rules given in effectively define how any XDM value in the is mapped to a value in the implicit data model of I-JSON. Values that cannot be mapped to I-JSON, such as function items, result in a serialization error.

A serialization error results if any error is raised during the canonicalization process.

JSON Output Method: the encoding Parameter

The encoding parameter identifies the encoding that the JSON output method MUST use to convert sequences of characters to sequences of bytes. Serializers are REQUIRED to support values of UTF-8 and UTF-16. A serialization error occurs if the serializer does not support the encoding specified by the encoding parameter. The serializer MUST raise the error. If the contains a character that cannot be represented in the encoding that the serializer is using for output, the serializer MUST raise a serialization error .

If an encoding other than UTF-8, UTF-16, UTF-32, US-ASCII, or an equivalent is specified for the encoding parameter, the output will (except in unusual circumstances) fail to conform to the definition of JSON in .

JSON Output Method: the indent Parameter

The indent parameter controls whether the serializer adjusts the whitespace in the serialized result so that a person will find it easier to read. If the indent parameter has the value true, the serializer MAY output additional whitespace characters adjacent to the JSON structural tokens. For all other values, the serializer MUST output no whitespace characters adjacent to the JSON structural tokens.

If indent and json-lines are both true, additional whitespace is allowed, but it MUST NOT include the characters U+000A or U+000D.

JSON Output Method: the normalization-form Parameter

The normalization-form parameter is applicable to the JSON output method. The values NFC and none MUST be supported by the serializer. A serialization error results if the value of the normalization-form parameter specifies a normalization form that is not supported by the serializer; the serializer MUST raise the error.

JSON Output Method: the media-type Parameter

The media-type parameter is applicable to the JSON output method. See for more information.

JSON Output Method: the use-character-maps Parameter

The use-character-maps parameter is applicable to the JSON output method. See for more information.

JSON Output Method: the byte-order-mark Parameter

The byte-order-mark parameter is applicable to the JSON output method. See for more information.

Serialized output containing a byte-order mark does not conform to the definition of JSON in (although conforming JSON parsers are allowed to tolerate the byte-order mark).

JSON Output Method: the escape-solidus Parameter

The escape-solidus parameter is applicable to the JSON output method. If the value is true, then the solidus character ("/") appearing in a string is escaped with a backslash (as "\/"). If the value is false, then it is not escaped.

In previous versions of this specification, the solidus was always escaped. Although JSON does not require this character to be escaped, doing so provides extra safety when the generated JSON is embedded in an HTML script element, since an unintended </script> end tag might otherwise cause the script to be prematurely terminated. In other situations, however, the escaping creates visual clutter and makes the output less readable.

JSON Output Method: the allow-duplicate-names Parameter

The allow-duplicate-names serialization parameter determines whether the presence of multiple keys in a map item with the same string value (e.g. the date 2014-10-01 and the string "2014-10-01") will or will not raise serialization error . If the value is true, such duplicate keys will result in duplicate object-member names in the JSON output and no error will be raised because of the duplicate names. If the value is false, such duplicate keys are an error ().

JSON Output Method: the json-node-output-method Parameter

The json-node-output-method serialization parameter determines how a node in the gets converted to a JSON value. If the value is one of xml, xhtml, html or text, then the node is converted to a JSON string by serializing the node using the output method specified by this parameter. If the value is xml or xhtml then the node is serialised with the additional serialization parameter omit-xml-declaration set to true. All other parameters, such as canonical, remain unchanged.

JSON Output Method: the json-lines Parameter

The json-lines serialization parameter determines if items are serialized according to the format, as described in .

Adaptive Output Method The serialization of maps retains the order of entries. The output of QNames reflects the new syntax for QName literals. A JNode is represented as jnode(K: V) where K is its ·selector· property and V is its ·content· property.

The Adaptive output method serializes the into a human readable form for the purposes of debugging query results. The intention of this is to allow any to be serialized without raising a serialization error. Sequence normalization is not performed for this output method.

Each item in the supplied sequence is serialized individually as follows, with an occurrence of the chosen item-separator between successive items.

A JNode is serialized as follows:

If the ·selector· property is absent (that is, for a parentless JNode), in the format jtree(V) where V is the adaptive serialization of the value of its ·content· property.

For example, the JNode selected by the expression jtree({ "a": [4, 5] }) is serialized as jtree({"a":[4,5]}).

If the ·selector· property is present, then in the format jnode(K: V) where K is the adaptive serialization of the value of its ·selector· property and V is the adaptive serialization of the value of its ·content· property.

For example, the JNode selected by the expression jtree({ "a": [4, 5] })/a is serialized as jnode("a":[4,5]).

A document, element, text, comment, or processing instruction node is serialized using the XML output method described in .

An attribute or namespace node is serialized as if it had a containing element node. For example an attribute node might be serialized as the string xsi:type="xs:integer"; a namespace node might be serialized as xmlns:sns="http://example.com/sample-namespace".

This may result in output of QNames containing prefixes whose binding is not displayed.

An atomic item is serialized as follows:

An instance of xs:boolean is serialized as true() or false().

An instance of xs:string, xs:untypedAtomic or xs:anyURI is serialized by enclosing the value in double quotation marks and doubling any quotes within the value; or optionally by enclosing the value in apostrophes and doubling any apostrophes within the value. The resulting value is then serialized using the Text output method described in .

The Text output method will apply character expansion and encoding rules to this string as specified by the serialization parameters.

An instance of xs:integer or xs:decimal is serialized by converting the value to a string using the fn:string function.

An instance of xs:double is serialized by applying the function format-number(?, '0.0##########################e0') using the following default decimal format properties:

Property name	Property value
`decimal-separator`	U+002E
`exponent-separator`	U+0065
`grouping-separator`	U+002C
`zero-digit`	U+0030
`digit`	U+0023
`infinity`	The string "INF"
`NaN`	The string "NaN"
`minus-sign`	U+002D

An instance of xs:NOTATION is serialized as a URI-qualified name (that is, in the form Q{uri}local).

An instance of xs:QName is serialized with a # character, followed by:

the local name if the name is in no namespace, or

the URI-qualified name otherwise (Q{uri}local).

An atomic item of any other type is serialized using the syntax of a constructor function: xs:TYPE("VAL") where TYPE is the name of the primitive type, and VAL is the result of applying the fn:string() function. For example, xs:date("2015-07-17"). The resulting string is then serialized using the Text output method described in .

An array item is serialized using the syntax of a , that is as [member, member, ... ]. The members, which in general are sequences, are serialized in the form (item, item, ...) where the items are serialized by applying these rules recursively. The items are separated by commas (not by the item-separator character). The enclosing parentheses are optional if the sequence has length one.

The serializer should avoid outputting the parentheses if it is able to determine the length of the sequence before serializing the first item; but it is allowed to output parentheses around a singleton if this avoids buffering data in memory.

A map item is serialized using the syntax of a without the optional map keyword, that is in the format {key:value, key:value, ...}. The key/value pairs in the serialized output retain the entry order of entries in the map. The key is serialized by applying the rules for serializing an atomic item. The values are serialized in the same way as the members of an array (see above).

A function item is serialized to the representation name#A where fn:name is a representation of the function name and A is the arity. If the function name is in one of the namespaces http://www.w3.org/2005/xpath-functions, http://www.w3.org/2005/xpath-functions/math, http://www.w3.org/2005/xpath-functions/map, http://www.w3.org/2005/xpath-functions/array or http://www.w3.org/2001/XMLSchema, then the name is output as a lexical QName using the conventional prefix fn, math, map, array, or xs as appropriate; if it is in any other namespace or in no namespace, then the name is output as a URI-qualified name (that is, Q{uri}local). If the function is anonymous, name is replaced by the string (anonymous-function).

The following examples illustrate this rule:

fn:exists#1 is serialized as function fn:exists#1

Q{http://www.w3.org/2005/xpath-functions}exists#1 is serialized as fn:exists#1

function($a) { $a } is serialized as (anonymous-function)#1

math:pi#0 is serialized as math:pi#0

Character maps are applied (a) when nodes are serialized using the XML output method, and (b) to any value represented as a string enclosed in quotation marks.

Optionally, in all the above constructs, characters whose visual representation is ambiguous (for example tab or non-breaking-space) may be represented in the form of an XML numeric character reference (for example 	 or  )

In many cases the serialization of an item conforms to the syntax of an XQuery expression whose result is that item. There are exceptions, however. For example, the syntax will not be valid XQuery in the case of free-standing attribute or namespace nodes, or QName values, or anonymous functions; and where it is valid XQuery, the result of evaluating the expression will not necessarily be identical to the original: for example, the distinction between strings and untypedAtomic items is lost.

If any value cannot be output because doing so would cause a serialization error, the behavior is implementation-defined.

It is implementation-defined whether the serialization process recovers from serialization errors when the Adaptive output method is used. If it does, it is implementation-defined what error indicator is used.

If the output is sent to a destination that allows hyperlinks to be included in the generated text, then the serializer MAY include implementation-dependent hyperlinks to provide additional information for example:

to allow the type of atomic items to be ascertained.

to allow the namespace binding of prefixes to be ascertained.

to provide further information about the cause of error indicators.

It is implementation-defined whether, when the Adaptive output method is used, a serializer includes hyperlinks in its output to record the types of atomic items, the bindings of namespace prefixes, the causes of error indicators, and other information.

If, when the Adaptive output method is used, a serializer includes hyperlinks in its output to record the types of atomic items, the bindings of namespace prefixes, the causes of error indicators, and other information, then it is implementation-dependent what hyperlinks are used and how they convey the information.

The Influence of Serialization Parameters upon the Adaptive Output Method Added the escape-solidus parameter for JSON serialization.

For some item types the Adaptive output method will delegate serialization to other output methods. With the exception of the byte-order-mark serialization parameter, all serialization parameters, if set, will be passed down to the serialization method that is applied to each item in the supplied sequence. Only the item-separator and byte-order-mark parameters are directly applicable to the Adaptive output method.

Adaptive Output Method: the omit-xml-declaration and standalone Parameters

The omit-xml-declaration and standalone parameters are not directly applicable to the Adaptive output method.

If these parameters call for an XML declaration to be serialized, then an XML declaration is to be output each time the Adaptive output method delegates the serialization of a node to the XML output method. If several node items appear in the sequence to be serialized or as values in maps or arrays to be serialized, then the output will contain several XML declarations.

Adaptive Output Method: the use-character-maps Parameter

The use-character-maps parameter is applicable to the Adaptive output method only as elsewhere specified.

Adaptive Output Method: the byte-order-mark Parameter

The byte-order-mark parameter is applicable to the Adaptive output method. See for more information.

A byte order mark can appear only once in the serialized output. Therefore, this parameter does not get passed down to any delegated output method.

Adaptive Output Method: the escape-solidus Parameter

The escape-solidus parameter is applicable to the Adaptive output method only as elsewhere specified.

Adaptive Output Method: the item-separator Parameter

The item-separator serialization parameter is directly applicable to the Adaptive output method. It specifies the string to be inserted between adjacent serialized items. If the item-separator parameter is absent, the character U+000A is used by the Adaptive output method as the item-separator value.

Character Maps

The use-character-maps parameter is a list of characters and corresponding string substitutions.

Character maps allow a specific character appearing in a text or attribute node or a string in the to be replaced with a specified string of characters during serialization. The string that is substituted is output "as is," and the serializer performs no checks that the resulting document is well-formed. This mechanism can therefore be used to introduce arbitrary markup in the serialized output. See of for examples of using character mapping in XSLT.

Character mapping is applied to the characters that actually appear in a text or attribute node or a string in the , before any other serialization operations such as escaping or Unicode Normalization are applied. If a character is mapped, then it is not subjected to XML or HTML escaping, nor to Unicode Normalization. The string that is substituted for a character is not validated or processed in any way by the serializer, except for translation into the target encoding. In particular, it is not subjected to XML or HTML escaping, it is not subjected to Unicode Normalization, and it is not subjected to further character mapping.

Character mapping is not applied to characters in text nodes whose parent elements are listed in the cdata-section-elements parameter, nor to characters for which output escaping has been disabled (disabling output escaping is an feature), nor to characters in attribute values that are subject to URI escaping defined for the HTML and XHTML output methods, unless URI escaping has been disabled using the escape-uri-attributes parameter in the output definition.

On serialization, occurrences of a character specified in the use-character-maps in text nodes, attribute values and strings are replaced by the corresponding string from the use-character-maps parameter.

Using a character map can result in non-well-formed documents if the string contains XML-significant characters. For example, it is possible to create documents containing unmatched start and end tags, references to entities that are not declared, or attributes that contain tags or unescaped quotation marks.

If a character is mapped, then it is not subjected to XML or HTML escaping.

A serialization error occurs if character mapping causes the output of a string containing a character that cannot be represented in the encoding that the serializer is using for output. The serializer MUST raise the error.

Conformance

Serialization is intended primarily as a component of a host language. A host language is another specification that includes, by reference, this specification and all of its requirements. A host language might be a programming language such as or , or it might be an application programming interface (API) intended to be used by programs written in some other high-level programming language. The use of the term language is not intended to preclude the possibility that this specification might be referenced outside the context of a programming language specification. This document relies on specifications that use it to specify conformance criteria for Serialization in their respective environments. Specifications that set conformance criteria for their use of Serialization MUST NOT change the semantic definitions of Serialization as given in this specification, except by subsetting and/or compatible extensions. It is the responsibility of the host language to specify how serialization errors are to be handled.

Certain facilities in this specification are described as producing implementation-defined results. A claim that asserts conformance with this specification MUST be accompanied by documentation stating the effect of each implementation-defined feature. For convenience, a non-normative checklist of implementation-defined features is provided at .

ReferencesNormative References Unicode Character Encoding Model, Unicode Consortium. Unicode Standard Annex #17. Unicode Normalization Forms, Unicode Consortium. Unicode Standard Annex #15. JSON Lines. Maintained by Ian Ward. The JSON Data Interchange Format, ECMA International. IETF. RFC 7159: The Javascript Object Notation (JSON) Data Interchange Format, T. Bray, Editor. Internet Engineering Task Force, March 2014. Available at: http://www.rfc-editor.org/rfc/rfc7159.txt Informative References The JSON Data Interchange Format, ECMA International. XSLT 2.0 and XQuery 1.0 Serialization (Second Edition), W3C Recommendation, Henry Zongaro, Norman Walsh, Joanne Tong, et. al., Editors. World Wide Web Consortium, 14 December 2010. This version is http://www.w3.org/TR/2010/REC-xslt-xquery-serialization-20101214/ XSLT and XQuery Serialization, W3C First Public Working Draft, Andrew Coleman, C. M. Sperberg-McQueen, et. al., Editors. World Wide Web Consortium, 24 April 2014.Schema for Serialization Parameters

The following schema describes the structure of a that can be used to specify the settings of serialization parameters using the mechanism described in .

A copy of this schema is available at http://www.w3.org/2017/01/xslt-xquery-serialization/schema-for-serialization-parameters.xsd.

Summary of Error Conditions

This document uses the err prefix which represents the same namespace URI (http://www.w3.org/2005/xqt-errors) as defined in . Use of this namespace prefix binding in this document is not normative.

It is an error if an item in S₆ in sequence normalization is an attribute node, a namespace node, or a function.

It is an error if the serializer is unable to satisfy the rules for either a well-formed XML document entity or a well-formed XML external general parsed entity, or both, except for content modified by the character expansion phase of serialization.

It is an error to specify the doctype-system parameter, or to specify the standalone parameter with a value other than omit, if the instance of the data model contains text nodes or multiple element nodes as children of the root node.

It is an error if the serialized result would contain an NCName that contains a character that is not permitted by the version of Namespaces in XML specified by the version parameter.

It is an error if the serialized result would contain a character that is not permitted by the version of XML specified by the version parameter.

It is an error if an output encoding other than UTF-8 or UTF-16 is requested and the serializer does not support that encoding.

It is an error if a character that cannot be represented in the encoding that the serializer is using for output appears in a context where character references are not allowed (for example if the character occurs in the name of an element).

It is an error if the omit-xml-declaration parameter has the value yes, true or 1, and the standalone attribute has a value other than omit; or the version parameter has a value other than 1.0 and the doctype-system parameter is specified.

It is an error if the output method is xml or xhtml, the value of the undeclare-prefixes parameter is one of yes, true or 1, and the value of the version parameter is 1.0.

It is an error if the value of the normalization-form parameter specifies a normalization form that is not supported by the serializer.

It is an error if the value of the normalization-form parameter is fully-normalized and any relevant construct of the result begins with a combining character.

It is an error if the serializer does not support the version of XML or HTML specified by the version parameter.

It is an error to use the HTML output method if characters which are permitted in XML but not in HTML appear in the instance of the data model.

It is an error to use the HTML output method when > appears within a processing instruction in the data model instance being serialized.

It is an error if a parameter value is invalid for the defined domain.

It is an error if evaluating an expression in order to extract the setting of a serialization parameter from a data model instance would yield an error.

It is an error if evaluating an expression in order to extract the setting of the use-character-maps serialization parameter from a data model instance would yield a sequence of length greater than one.

It is an error if an instance of the data model used to specify the settings of serialization parameters specifies the value of the same parameter more than once.

It is an error if a numeric value being serialized using the JSON output method cannot be represented in the JSON grammar (e.g. +INF, -INF, NaN).

It is an error if a sequence being serialized using the JSON output method includes items for which no rules are provided in the appropriate section of the serialization rules.

It is an error if a map being serialized using the JSON output method has two keys with the same string value, unless the allow-duplicate-names has the value yes, true or 1.

It is an error if a sequence being serialized using the JSON output method is of length greater than one.

It is an error if the processing the rules for canonicalization result in a serialization failure.

List of URI Attributes

The following list of attributes are declared as type %URI or %UriList for a given HTML or XHTML element, with the exception of the name attribute for element A which is not a URI type. The name attribute for element A SHOULD be escaped as is recommended by the HTML Recommendation in Appendix B.2.1.

Attributes	Elements
action	FORM
archive	OBJECT
background	BODY
cite	BLOCKQUOTE, DEL, INS, Q
classid	OBJECT
codebase	APPLET, OBJECT
data	OBJECT
datasrc	BUTTON, DIV, INPUT, OBJECT, SELECT, SPAN, TABLE, TEXTAREA
for	SCRIPT
formaction	BUTTON, INPUT
href	A, AREA, BASE, LINK
icon	COMMAND
longdesc	FRAME, IFRAME, IMG
manifest	HTML
name	A
poster	VIDEO
profile	HEAD
src	AUDIO, EMBED, FRAME, IFRAME, IMG, INPUT, SCRIPT, SOURCE, TRACK, VIDEO
usemap	IMG, INPUT, OBJECT
value	INPUT

Glossary

Checklist of Implementation-Defined and Implementation-Dependent Features

This appendix provides a summary of Serialization features whose effect is explicitly implementation-defined or implementation-dependent.

Checklist of Implementation-Defined Features

The following list describes Serialization features whose effect is explicitly implementation-defined. The conformance rules (see ) require vendors to provide documentation that explains how these choices have been exercised.

Checklist of Implementation-Dependent Features

The following list describes Serialization features whose effect is explicitly implementation-dependent. The conformance rules (see ) do not require vendors or specifications which define conformance criteria for serialization to provide documentation that explains how these choices have been exercised.

Change Log

This appendix lists changes made in version 4.0 of this specification.

Backward compatibility

This section summarizes the extent to which this specification is compatible with previous versions.

Version 4.0 is fully backwards compatible with version 3.1, except as noted below:

The output of QNames with the has been adapted to reflect the new QName literal syntax: QName strings are now prefixed with the # character.