FunctionQName | ::= | (QNameToken | Ascending | Descending | External | Greatest | Least | "NaN" | "allowing" | "ancestor" | "ancestor-or-self" | "and" | "as" | "at" | "base-uri" | "boundary-space" | "by" | "case" | "cast" | "castable" | "catch" | "child" | "collation" | "construction" | "context" | "copy-namespaces" | "count" | "decimal-format" | "decimal-separator" | "declare" | "default" | "descendant" | "descendant-or-self" | "digit" | "div" | "document" | "else" | "empty" | "encoding" | "end" | "eq" | "every" | "except" | "following" | "following-sibling" | "for" | "ge" | "group" | "grouping-separator" | "gt" | "idiv" | "import" | "in" | "infinity" | "inherit" | "instance" | "intersect" | "is" | "lax" | "le" | "let" | "lt" | "minus-sign" | "mod" | "module" | "namespace" | "ne" | "next" | "no-inherit" | "no-preserve" | "of" | "only" | "option" | "or" | "order" | "ordered" | "ordering" | "parent" | "pattern-separator" | "per-mille" | "percent" | "preceding" | "preceding-sibling" | "preserve" | "previous" | "return" | "satisfies" | "schema" | "self" | "sliding" | "some" | "stable" | "start" | "strict" | "strip" | "then" | "to" | "treat" | "try" | "tumbling" | "type" | "union" | "unordered" | "validate" | "variable" | "version" | "when" | "where" | "window" | "xquery" | "zero-digit") |