http://www.w3.org/2005/xpath-functions

Constructs an xs:QName value given a namespace URI and a lexical QName.

This function is deterministic, context-independent, and focus-independent.

The namespace URI in the returned QName is taken from $paramURI. If $paramURI is the zero-length string or the empty sequence, it represents "no namespace".

The prefix (or absence of a prefix) in $paramQName is retained in the returned xs:QName value.

The local name in the result is taken from the local part of $paramQName.

A dynamic error is raised if $paramQName does not have the correct lexical form for an instance of xs:QName.

A dynamic error is raised if $paramURI is the zero-length string or the empty sequence, and the value of $paramQName contains a colon (:).

A dynamic error may be raised if $paramURI is not a valid URI (XML Namespaces 1.0) or IRI (XML Namespaces 1.1).

Returns the absolute value of $arg.

This function is deterministic, context-independent, and focus-independent.

General rules: see .

If $arg is negative the function returns -$arg, otherwise it returns $arg.

If the type of $arg is one of the four numeric types xs:float, xs:double, xs:decimal or xs:integer the type of the result is the same as the type of $arg. If the type of $arg is a type derived from one of the numeric types, the result is an instance of the base numeric type.

For xs:float and xs:double arguments, if the argument is positive zero or negative zero, then positive zero is returned. If the argument is positive or negative infinity, positive infinity is returned.

For detailed type semantics, see [Formal Semantics].

The expression fn:abs(10.5) returns 10.5.

The expression fn:abs(-10.5) returns 10.5.

Adjusts an xs:date value to a specific timezone, or to no timezone at all; the result is the date in the target timezone that contains the starting instant of the supplied date.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is the value of $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the local value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then the function returns the value of the expression:

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or is not an integral number of minutes.

Adjusts an xs:date value to a specific timezone, or to no timezone at all; the result is the date in the target timezone that contains the starting instant of the supplied date.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is the value of $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the local value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then the function returns the value of the expression:

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or is not an integral number of minutes.

Adjusts an xs:dateTime value to a specific timezone, or to no timezone at all.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the local value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then the result is the xs:dateTime value that is equal to $arg and that has a timezone component equal to $timezone.

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or is not an integral number of minutes.

Adjusts an xs:dateTime value to a specific timezone, or to no timezone at all.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the local value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then the result is the xs:dateTime value that is equal to $arg and that has a timezone component equal to $timezone.

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or is not an integral number of minutes.

Adjusts an xs:time value to a specific timezone, or to no timezone at all.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the localized value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then:

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or if does not contain an integral number of minutes.

Adjusts an xs:time value to a specific timezone, or to no timezone at all.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

If $timezone is not specified, then the effective value of $timezone is the value of the implicit timezone in the dynamic context.

If $arg is the empty sequence, then the function returns the empty sequence.

If $arg does not have a timezone component and $timezone is the empty sequence, then the result is $arg.

If $arg does not have a timezone component and $timezone is not the empty sequence, then the result is $arg with $timezone as the timezone component.

If $arg has a timezone component and $timezone is the empty sequence, then the result is the localized value of $arg without its timezone component.

If $arg has a timezone component and $timezone is not the empty sequence, then:

A dynamic error is raised if $timezone is less than -PT14H or greater than PT14H or if does not contain an integral number of minutes.

Analyzes a string using a regular expression, returning an XML structure that identifies which parts of the input string matched or failed to match the regular expression, and in the case of matched substrings, which substrings matched each capturing group in the regular expression.

This function is nondeterministic, context-independent, and focus-independent.

The effect of calling the first version of this function (omitting the argument $flags) is the same as the effect of calling the second version with the $flags argument set to a zero-length string. Flags are defined in .

The $flags argument is interpreted in the same way as for the fn:matches function.

If $input is the empty sequence the function behaves as if $input were the zero-length string. In this situation the result will be an element node with no children.

The function returns an element node whose local name is analyze-string-result. This element and all its descendant elements have the namespace URI http://www.w3.org/2005/xpath-functions. The namespace prefix is . The children of this element are a sequence of fn:match and fn:non-match elements. This sequence is formed by breaking the $input string into a sequence of strings, returning any substring that matches $pattern as the content of a match element, and any intervening substring as the content of a non-match element.

More specifically, the function starts at the beginning of the input string and attempts to find the first substring that matches the regular expression. If there are several matches, the first match is defined to be the one whose starting position comes first in the string. If several alternatives within the regular expression both match at the same position in the input string, then the match that is chosen is the first alternative that matches. For example, if the input string is The quick brown fox jumps and the regular expression is jump|jumps, then the match that is chosen is jump.

Having found the first match, the instruction proceeds to find the second and subsequent matches by repeating the search, starting at the first character that was not included in the previous match.

The input string is thus partitioned into a sequence of substrings, some of which match the regular expression, others which do not match it. Each substring will contain at least one character. This sequence is represented in the result by the sequence of fn:match and fn:non-match children of the returned element node; the string value of the fn:match or fn:non-match element will be the corresponding substring of $input, and the string value of the returned element node will therefore be the same as $input.

The content of an fn:non-match element is always a single text node.

The content of a fn:match element, however, is in general a sequence of text nodes and fn:group element children. An fn:group element with a nr attribute having the integer value N identifies the substring captured by the Nth parenthesized sub-expression in the regular expression. For each capturing subexpression there will be at most one corresponding fn:group element in each fn:match element in the result.

If the function is called twice with the same arguments, it is whether the two calls return the same element node or distinct (but deep equal) element nodes. In this respect it is nondeterministic.

The base URI of the element nodes in the result is

A schema is defined for the structure of the returned element, containing the definitions below. The returned element and its descendants will have type annotations obtained by validating the returned element against this schema, unless the function is used in an environment where type annotations are not supported (for example, a Basic XSLT Processor), in which case the elements will all be annotated as xs:untyped and the attributes as xs:untypedAtomic.

<?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.w3.org/2005/xpath-functions" xmlns:fn="http://www.w3.org/2005/xpath-functions" elementFormDefault="qualified"> <xs:element name="analyze-string-result" type="fn:analyze-string-result-type"/> <xs:element name="match" type="fn:match-type"/> <xs:element name="non-match" type="xs:string"/> <xs:element name="group" type="fn:group-type"/> <xs:complexType name="analyze-string-result-type" mixed="true"> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element ref="fn:match"/> <xs:element ref="fn:non-match"/> </xs:choice> </xs:complexType> <xs:complexType name="match-type" mixed="true"> <xs:sequence> <xs:element ref="fn:group" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> <xs:complexType name="group-type" mixed="true"> <xs:sequence> <xs:element ref="fn:group" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> <xs:attribute name="nr" type="xs:positiveInteger"/> </xs:complexType> </xs:schema>

A dynamic error is raised if the value of $pattern is invalid according to the rules described in section .

A dynamic error is raised if the value of $flags is invalid according to the rules described in section .

A dynamic error is raised if the supplied $pattern matches a zero-length string, that is, if fn:matches("", $pattern, $flags) returns true.

Analyzes a string using a regular expression, returning an XML structure that identifies which parts of the input string matched or failed to match the regular expression, and in the case of matched substrings, which substrings matched each capturing group in the regular expression.

This function is nondeterministic, context-independent, and focus-independent.

The effect of calling the first version of this function (omitting the argument $flags) is the same as the effect of calling the second version with the $flags argument set to a zero-length string. Flags are defined in .

The $flags argument is interpreted in the same way as for the fn:matches function.

If $input is the empty sequence the function behaves as if $input were the zero-length string. In this situation the result will be an element node with no children.

The function returns an element node whose local name is analyze-string-result. This element and all its descendant elements have the namespace URI http://www.w3.org/2005/xpath-functions. The namespace prefix is . The children of this element are a sequence of fn:match and fn:non-match elements. This sequence is formed by breaking the $input string into a sequence of strings, returning any substring that matches $pattern as the content of a match element, and any intervening substring as the content of a non-match element.

More specifically, the function starts at the beginning of the input string and attempts to find the first substring that matches the regular expression. If there are several matches, the first match is defined to be the one whose starting position comes first in the string. If several alternatives within the regular expression both match at the same position in the input string, then the match that is chosen is the first alternative that matches. For example, if the input string is The quick brown fox jumps and the regular expression is jump|jumps, then the match that is chosen is jump.

Having found the first match, the instruction proceeds to find the second and subsequent matches by repeating the search, starting at the first character that was not included in the previous match.

The input string is thus partitioned into a sequence of substrings, some of which match the regular expression, others which do not match it. Each substring will contain at least one character. This sequence is represented in the result by the sequence of fn:match and fn:non-match children of the returned element node; the string value of the fn:match or fn:non-match element will be the corresponding substring of $input, and the string value of the returned element node will therefore be the same as $input.

The content of an fn:non-match element is always a single text node.

The content of a fn:match element, however, is in general a sequence of text nodes and fn:group element children. An fn:group element with a nr attribute having the integer value N identifies the substring captured by the Nth parenthesized sub-expression in the regular expression. For each capturing subexpression there will be at most one corresponding fn:group element in each fn:match element in the result.

If the function is called twice with the same arguments, it is whether the two calls return the same element node or distinct (but deep equal) element nodes. In this respect it is nondeterministic.

The base URI of the element nodes in the result is

A schema is defined for the structure of the returned element, containing the definitions below. The returned element and its descendants will have type annotations obtained by validating the returned element against this schema, unless the function is used in an environment where type annotations are not supported (for example, a Basic XSLT Processor), in which case the elements will all be annotated as xs:untyped and the attributes as xs:untypedAtomic.

<?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.w3.org/2005/xpath-functions" xmlns:fn="http://www.w3.org/2005/xpath-functions" elementFormDefault="qualified"> <xs:element name="analyze-string-result" type="fn:analyze-string-result-type"/> <xs:element name="match" type="fn:match-type"/> <xs:element name="non-match" type="xs:string"/> <xs:element name="group" type="fn:group-type"/> <xs:complexType name="analyze-string-result-type" mixed="true"> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element ref="fn:match"/> <xs:element ref="fn:non-match"/> </xs:choice> </xs:complexType> <xs:complexType name="match-type" mixed="true"> <xs:sequence> <xs:element ref="fn:group" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> <xs:complexType name="group-type" mixed="true"> <xs:sequence> <xs:element ref="fn:group" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> <xs:attribute name="nr" type="xs:positiveInteger"/> </xs:complexType> </xs:schema>

A dynamic error is raised if the value of $pattern is invalid according to the rules described in section .

A dynamic error is raised if the value of $flags is invalid according to the rules described in section .

A dynamic error is raised if the supplied $pattern matches a zero-length string, that is, if fn:matches("", $pattern, $flags) returns true.

Returns a list of environment variable names that are suitable for passing to fn:environment-variable, as a (possibly empty) sequence of strings.

This function is deterministic, context-dependent, and focus-independent. It depends on environment variables.

The function returns a sequence of strings, being the names of the environment variables in the dynamic context in some implementation-dependent order.

The function is deterministic: that is, the set of available environment variables does not vary during evaluation.

The function returns a list of strings, containing no duplicates.

It is intended that the strings in this list should be suitable for passing to fn:environment-variable.

See also the note on security under the definition of the fn:environment-variable function. If access to environment variables has been disabled, fn:available-environment-variables always returns the empty sequence.

Returns a list of environment variable names that are suitable for passing to fn:environment-variable, as a (possibly empty) sequence of strings.

This function is deterministic, context-dependent, and focus-independent. It depends on environment variables.

The function returns a sequence of strings, being the names of the environment variables in the dynamic context in some implementation-dependent order.

The function is deterministic: that is, the set of available environment variables does not vary during evaluation.

The function returns a list of strings, containing no duplicates.

It is intended that the strings in this list should be suitable for passing to fn:environment-variable.

See also the note on security under the definition of the fn:environment-variable function. If access to environment variables has been disabled, fn:available-environment-variables always returns the empty sequence.

Returns the average of the values in the input sequence $arg, that is, the sum of the values divided by the number of values.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence, the empty sequence is returned.

If $arg contains values of type xs:untypedAtomic they are cast to xs:double.

Duration values must either all be xs:yearMonthDuration values or must all be xs:dayTimeDuration values. For numeric values, the numeric promotion rules defined in are used to promote all values to a single common type. After these operations, $arg must contain items of a single type, which must be one of the four numeric types, xs:yearMonthDuration or xs:dayTimeDuration or one if its subtypes.

The function returns the average of the values as sum($arg) div count($arg); but the implementation may use an otherwise equivalent algorithm that avoids arithmetic overflow.

For detailed type semantics, see [Formal Semantics].

A type error is raised if the input sequence contains items of incompatible types, as described above.

Returns the base URI of a node.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

The zero-argument version of the function returns the base URI of the context node: it is equivalent to calling fn:base-uri(.).

The single-argument version of the function behaves as follows:

See also fn:static-base-uri.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the base URI of a node.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

The zero-argument version of the function returns the base URI of the context node: it is equivalent to calling fn:base-uri(.).

The single-argument version of the function behaves as follows:

See also fn:static-base-uri.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Computes the effective boolean value of the sequence $arg.

The function computes the effective boolean value of a sequence, defined according to the following rules. See also .

The static semantics of this function are described in [Formal Semantics].

The result of this function is not necessarily the same as $arg cast as xs:boolean. For example, fn:boolean("false") returns the value true whereas "false" cast as xs:boolean (which can also be written xs:boolean("false")) returns false.

let $abc := ("a", "b", "")

fn:boolean($abc) raises a type error .

The expression fn:boolean($abc[1]) returns true().

The expression fn:boolean($abc[0]) returns false().

The expression fn:boolean($abc[3]) returns false().

Rounds $arg upwards to a whole number.

This function is deterministic, context-independent, and focus-independent.

General rules: see .

The function returns the smallest (closest to negative infinity) number with no fractional part that is not less than the value of $arg.

If the type of $arg is one of the four numeric types xs:float, xs:double, xs:decimal or xs:integer the type of the result is the same as the type of $arg. If the type of $arg is a type derived from one of the numeric types, the result is an instance of the base numeric type.

For xs:float and xs:double arguments, if the argument is positive zero, then positive zero is returned. If the argument is negative zero, then negative zero is returned. If the argument is less than zero and greater than -1, negative zero is returned.

For detailed type semantics, see [Formal Semantics].

The expression fn:ceiling(10.5) returns 11.

The expression fn:ceiling(-10.5) returns -10.

Returns true if two strings are equal, considered codepoint-by-codepoint.

This function is deterministic, context-independent, and focus-independent.

If either argument is the empty sequence, the function returns the empty sequence.

Otherwise, the function returns true or false depending on whether the value of $comparand1 is equal to the value of $comparand2, according to the Unicode codepoint collation (http://www.w3.org/2005/xpath-functions/collation/codepoint).

This function allows xs:anyURI values to be compared without having to specify the Unicode codepoint collation.

Creates an xs:string from a sequence of codepoints.

This function is deterministic, context-independent, and focus-independent.

The function returns the string made up from the characters whose Unicode codepoints are supplied in $arg. This will be the zero-length string if $arg is the empty sequence.

A dynamic error is raised if any of the codepoints in $arg is not a permitted XML character.

Creates an xs:string from a sequence of codepoints.

This function is deterministic, context-independent, and focus-independent.

The function returns the string made up from the characters whose Unicode codepoints are supplied in $arg. This will be the zero-length string if $arg is the empty sequence.

A dynamic error is raised if any of the codepoints in $arg is not a permitted XML character.

Returns a sequence of nodes representing a collection of documents indentified by a collection URI; or a default collection if no URI is supplied.

This function is deterministic, context-dependent, and focus-independent. It depends on available node collections, and static base uri.

This function takes an xs:string as argument and returns a sequence of nodes obtained by interpreting $arg as an xs:anyURI and resolving it according to the mapping specified in Available node collections described in .

If Available node collections provides a mapping from this string to a sequence of nodes, the function returns that sequence. If Available node collections maps the string to an empty sequence, then the function returns an empty sequence.

If $arg is not specified, the function returns the sequence of the nodes in the default node collection in the dynamic context. See .

If the value of $arg is a relative xs:anyURI, it is resolved against the value of the base-URI property from the static context.

If $arg is the empty sequence, the function behaves as if it had been called without an argument. See above.

By default, this function is deterministic. This means that repeated calls on the function with the same argument will return the same result. However, for performance reasons, implementations may provide a user option to evaluate the function without a guarantee of determinism. The manner in which any such option is provided is . If the user has not selected such an option, a call to this function must either return a deterministic result or must raise a dynamic error .

There is no requirement that the returned nodes should be in document order, nor is there a requirement that the result should contain no duplicates.

For detailed type semantics, see [Formal Semantics].

A dynamic error is raised if no URI is supplied and the value of the default collection is absent.

A dynamic error is raised if available node collections provides no mapping for the absolutized URI.

A dynamic error is raised if $arg is not a valid xs:anyURI.

Returns a sequence of nodes representing a collection of documents indentified by a collection URI; or a default collection if no URI is supplied.

This function is deterministic, context-dependent, and focus-independent. It depends on available node collections, and static base uri.

This function takes an xs:string as argument and returns a sequence of nodes obtained by interpreting $arg as an xs:anyURI and resolving it according to the mapping specified in Available node collections described in .

If Available node collections provides a mapping from this string to a sequence of nodes, the function returns that sequence. If Available node collections maps the string to an empty sequence, then the function returns an empty sequence.

If $arg is not specified, the function returns the sequence of the nodes in the default node collection in the dynamic context. See .

If the value of $arg is a relative xs:anyURI, it is resolved against the value of the base-URI property from the static context.

If $arg is the empty sequence, the function behaves as if it had been called without an argument. See above.

By default, this function is deterministic. This means that repeated calls on the function with the same argument will return the same result. However, for performance reasons, implementations may provide a user option to evaluate the function without a guarantee of determinism. The manner in which any such option is provided is . If the user has not selected such an option, a call to this function must either return a deterministic result or must raise a dynamic error .

There is no requirement that the returned nodes should be in document order, nor is there a requirement that the result should contain no duplicates.

For detailed type semantics, see [Formal Semantics].

A dynamic error is raised if no URI is supplied and the value of the default collection is absent.

A dynamic error is raised if available node collections provides no mapping for the absolutized URI.

A dynamic error is raised if $arg is not a valid xs:anyURI.

Returns -1, 0, or 1, depending on whether $comparand1 collates before, equal to, or after $comparand2 according to the rules of a selected collation.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

Returns -1, 0, or 1, depending on whether the value of the $comparand1 is respectively less than, equal to, or greater than the value of $comparand2, according to the rules of the collation that is used.

The collation used by this function is determined according to the rules in .

If either $comparand1 or $comparand2 is the empty sequence, the function returns the empty sequence.

This function, called with the first signature, defines the semantics of the "eq", "ne", "gt", "lt", "le" and "ge" operators on xs:string values.

The expression fn:compare('abc', 'abc') returns 0.

The expression fn:compare('Strasse', 'Straße') returns 0. (Assuming the default collation includes provisions that equate ss and the (German) character ß (sharp-s). Otherwise, the returned value depends on the semantics of the default collation.).

The expression fn:compare('Strasse', 'Straße', 'http://example.com/deutsch') returns 0. (Assuming the collation identified by the URI http://example.com/deutsch includes provisions that equate ss and the (German) character ß (sharp-s). Otherwise, the returned value depends on the semantics of that collation.).

The expression fn:compare('Strassen', 'Straße') returns 1. (Assuming the default collation includes provisions that treat differences between ss and the (German) character ß (sharp-s) with less strength than the differences between the base characters, such as the final n. ).

Returns -1, 0, or 1, depending on whether $comparand1 collates before, equal to, or after $comparand2 according to the rules of a selected collation.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

Returns -1, 0, or 1, depending on whether the value of the $comparand1 is respectively less than, equal to, or greater than the value of $comparand2, according to the rules of the collation that is used.

The collation used by this function is determined according to the rules in .

If either $comparand1 or $comparand2 is the empty sequence, the function returns the empty sequence.

This function, called with the first signature, defines the semantics of the "eq", "ne", "gt", "lt", "le" and "ge" operators on xs:string values.

The expression fn:compare('abc', 'abc') returns 0.

The expression fn:compare('Strasse', 'Straße') returns 0. (Assuming the default collation includes provisions that equate ss and the (German) character ß (sharp-s). Otherwise, the returned value depends on the semantics of the default collation.).

The expression fn:compare('Strasse', 'Straße', 'http://example.com/deutsch') returns 0. (Assuming the collation identified by the URI http://example.com/deutsch includes provisions that equate ss and the (German) character ß (sharp-s). Otherwise, the returned value depends on the semantics of that collation.).

The expression fn:compare('Strassen', 'Straße') returns 1. (Assuming the default collation includes provisions that treat differences between ss and the (German) character ß (sharp-s) with less strength than the differences between the base characters, such as the final n. ).

Returns the concatenation of the string values of the arguments.

The two-argument form of this function defines the semantics of the "||" operator.

This function is deterministic, context-independent, and focus-independent.

This function accepts two or more xs:anyAtomicType arguments and casts each one to xs:string. The function returns the xs:string that is the concatenation of the values of its arguments after conversion. If any argument is the empty sequence, that argument is treated as the zero-length string.

The fn:concat function is specified to allow two or more arguments, which are concatenated together. This is the only function specified in this document that allows a variable number of arguments. This capability is retained for compatibility with .

Returns true if the string $arg1 contains $arg2 as a substring, taking collations into account.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

If the value of $arg1 or $arg2 is the empty sequence, or contains only ignorable collation units, it is interpreted as the zero-length string.

If the value of $arg2 is the zero-length string, then the function returns true.

If the value of $arg1 is the zero-length string, the function returns false.

The collation used by this function is determined according to the rules in .

The function returns an xs:boolean indicating whether or not the value of $arg1 contains (at the beginning, at the end, or anywhere within) at least one sequence of collation units that provides a minimal match to the collation units in the value of $arg2, according to the collation that is used.

A dynamic error may be raised if the specified collation does not support collation units.

Returns true if the string $arg1 contains $arg2 as a substring, taking collations into account.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

If the value of $arg1 or $arg2 is the empty sequence, or contains only ignorable collation units, it is interpreted as the zero-length string.

If the value of $arg2 is the zero-length string, then the function returns true.

If the value of $arg1 is the zero-length string, the function returns false.

The collation used by this function is determined according to the rules in .

The function returns an xs:boolean indicating whether or not the value of $arg1 contains (at the beginning, at the end, or anywhere within) at least one sequence of collation units that provides a minimal match to the collation units in the value of $arg2, according to the collation that is used.

A dynamic error may be raised if the specified collation does not support collation units.

Returns the number of items in a sequence.

This function is deterministic, context-independent, and focus-independent.

The function returns the number of items in the value of $arg.

Returns 0 if $arg is the empty sequence.

Returns the current date.

This function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

Returns xs:date(fn:current-dateTime()). This is an xs:date (with timezone) that is current at some time during the evaluation of a query or transformation in which fn:current-date is executed.

This function is . The precise instant during the query or transformation represented by the value of fn:current-date is .

The returned date will always have an associated timezone, which will always be the same as the implicit timezone in the dynamic context

Returns the current date and time (with timezone).

This function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

Returns the current dateTime (with timezone) from the dynamic context. (See .) This is an xs:dateTime that is current at some time during the evaluation of a query or transformation in which fn:current-dateTime is executed.

This function is . The precise instant during the query or transformation represented by the value of fn:current-dateTime() is .

If the implementation supports data types from XSD 1.1 then the returned value will be an instance of xs:dateTimeStamp. Otherwise, the only guarantees are that it will be an instance of xs:dateTime and will have a timezone component.

The returned xs:dateTime will always have an associated timezone, which will always be the same as the implicit timezone in the dynamic context

Returns the current time.

This function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

Returns xs:time(fn:current-dateTime()). This is an xs:time (with timezone) that is current at some time during the evaluation of a query or transformation in which fn:current-time is executed.

This function is . The precise instant during the query or transformation represented by the value of fn:current-time() is .

The returned time will always have an associated timezone, which will always be the same as the implicit timezone in the dynamic context

Returns the result of atomizing a sequence, that is, replacing all nodes in the sequence by their typed values.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

The result of fn:data is the sequence of atomic values produced by applying the following rules to each item in $arg:

A type error is raised if an item in the sequence $arg is a node that does not have a typed value.

A type error is raised if an item in the sequence $arg is a function item.

A dynamic error is raised if $arg is omitted and the context item is absent.

Returns the result of atomizing a sequence, that is, replacing all nodes in the sequence by their typed values.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

The result of fn:data is the sequence of atomic values produced by applying the following rules to each item in $arg:

A type error is raised if an item in the sequence $arg is a node that does not have a typed value.

A type error is raised if an item in the sequence $arg is a function item.

A dynamic error is raised if $arg is omitted and the context item is absent.

Returns an xs:dateTime value created by combining an xs:date and an xs:time.

This function is deterministic, context-independent, and focus-independent.

If either $arg1 or $arg2 is the empty sequence the function returns the empty sequence.

Otherwise, the function returns an xs:dateTime whose date component is equal to $arg1 and whose time component is equal to $arg2.

The timezone of the result is computed as follows:

A dynamic error is raised if the two arguments both have timezones and the timezones are different.

Returns the day component of an xs:date.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence, the function returns the empty sequence.

Otherwise, the function returns an xs:integer between 1 and 31, both inclusive, representing the day component in the localized value of $arg.

The expression fn:day-from-date(xs:date("1999-05-31-05:00")) returns 31.

The expression fn:day-from-date(xs:date("2000-01-01+05:00")) returns 1.

Returns the number of days in a duration.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence, the function returns the empty sequence.

Otherwise, the function returns an xs:integer representing the days component in the value of $arg. The result is obtained by casting $arg to an xs:dayTimeDuration (see ) and then computing the days component as described in .

If $arg is a negative duration then the result will be negative..

If $arg is an xs:yearMonthDuration the function returns 0.

The expression fn:days-from-duration(xs:dayTimeDuration("P3DT10H")) returns 3.

The expression fn:days-from-duration(xs:dayTimeDuration("P3DT55H")) returns 5.

The expression fn:days-from-duration(xs:yearMonthDuration("P3Y5M")) returns 0.

This function assesses whether two sequences are deep-equal to each other. To be deep-equal, they must contain items that are pairwise deep-equal; and for two items to be deep-equal, they must either be atomic values that compare equal, or nodes of the same kind, with the same name, whose children are deep-equal.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The $collation argument identifies a collation which is used at all levels of recursion when strings are compared (but not when names are compared), according to the rules in .

If the two sequences are both empty, the function returns true.

If the two sequences are of different lengths, the function returns false.

If the two sequences are of the same length, the function returns true if and only if every item in the sequence $parameter1 is deep-equal to the item at the same position in the sequence $parameter2. The rules for deciding whether two items are deep-equal follow.

Call the two items $i1 and $i2 respectively.

If $i1 and $i2 are both atomic values, they are deep-equal if and only if ($i1 eq $i2) is true, or if both values are NaN. If the eq operator is not defined for $i1 and $i2, the function returns false.

If one of the pair $i1 or $i2 is an atomic value and the other is not, the function returns false.

If $i1 and $i2 are both nodes, they are compared as described below:

A type error is raised if either input sequence contains a function item.

This function assesses whether two sequences are deep-equal to each other. To be deep-equal, they must contain items that are pairwise deep-equal; and for two items to be deep-equal, they must either be atomic values that compare equal, or nodes of the same kind, with the same name, whose children are deep-equal.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The $collation argument identifies a collation which is used at all levels of recursion when strings are compared (but not when names are compared), according to the rules in .

If the two sequences are both empty, the function returns true.

If the two sequences are of different lengths, the function returns false.

If the two sequences are of the same length, the function returns true if and only if every item in the sequence $parameter1 is deep-equal to the item at the same position in the sequence $parameter2. The rules for deciding whether two items are deep-equal follow.

Call the two items $i1 and $i2 respectively.

If $i1 and $i2 are both atomic values, they are deep-equal if and only if ($i1 eq $i2) is true, or if both values are NaN. If the eq operator is not defined for $i1 and $i2, the function returns false.

If one of the pair $i1 or $i2 is an atomic value and the other is not, the function returns false.

If $i1 and $i2 are both nodes, they are compared as described below:

A type error is raised if either input sequence contains a function item.

Returns the value of the default collation property from the static context.

This function is deterministic, context-dependent, and focus-independent. It depends on collations.

Returns the value of the default collation property from the static context. Components of the static context are discussed in .

The default collation property can never be absent. If it is not explicitly defined, a system defined default can be invoked. If this is not provided, the Unicode codepoint collation (http://www.w3.org/2005/xpath-functions/collation/codepoint) is used.

Returns the values that appear in a sequence, with duplicates eliminated.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The function returns the sequence that results from removing from $arg all but one of a set of values that are equal to one another. Values are compared using the eq operator, subject to the caveats defined below.

Values of type xs:untypedAtomic are compared as if they were of type xs:string.

Values that cannot be compared, because the eq operator is not defined for their types, are considered to be distinct.

The collation used by this function is determined according to the rules in . This collation is used when string comparison is required.

For xs:float and xs:double values, positive zero is equal to negative zero and, although NaN does not equal itself, if $arg contains multiple NaN values a single NaN is returned.

If xs:dateTime, xs:date or xs:time values do not have a timezone, they are considered to have the implicit timezone provided by the dynamic context for the purpose of comparison. Note that xs:dateTime, xs:date or xs:time values can compare equal even if their timezones are different.

The order in which the sequence of values is returned is .

Which value of a set of values that compare equal is returned is .

The static type of the result is a sequence of prime types as defined in [Formal Semantics].

If $arg is the empty sequence, the function returns the empty sequence.

Returns the values that appear in a sequence, with duplicates eliminated.

The one-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The function returns the sequence that results from removing from $arg all but one of a set of values that are equal to one another. Values are compared using the eq operator, subject to the caveats defined below.

Values of type xs:untypedAtomic are compared as if they were of type xs:string.

Values that cannot be compared, because the eq operator is not defined for their types, are considered to be distinct.

The collation used by this function is determined according to the rules in . This collation is used when string comparison is required.

For xs:float and xs:double values, positive zero is equal to negative zero and, although NaN does not equal itself, if $arg contains multiple NaN values a single NaN is returned.

If xs:dateTime, xs:date or xs:time values do not have a timezone, they are considered to have the implicit timezone provided by the dynamic context for the purpose of comparison. Note that xs:dateTime, xs:date or xs:time values can compare equal even if their timezones are different.

The order in which the sequence of values is returned is .

Which value of a set of values that compare equal is returned is .

The static type of the result is a sequence of prime types as defined in [Formal Semantics].

If $arg is the empty sequence, the function returns the empty sequence.

The function returns true if and only if the function call fn:doc($uri) would return a document node.

This function is deterministic, context-dependent, and focus-independent. It depends on available documents, and static base uri.

If $uri is an empty sequence, this function returns false.

If a call on fn:doc($uri) would return a document node, this function returns true.

A dynamic error is raised if $uri is not a valid URI according to the rules applied by the implementation of fn:doc.

Otherwise, this function returns false.

If this function returns true, then calling fn:doc($uri) within the same must return a document node. However, if nondeterministic processing has been selected for the fn:doc function, this guarantee is lost.

Retrieves a document using a URI supplied as an xs:string, and returns the corresponding document node.

This function is deterministic, context-dependent, and focus-independent. It depends on available documents, and static base uri.

If $uri is the empty sequence, the result is an empty sequence.

If $uri is a relative URI reference, it is resolved relative to the value of the Static Base URI property from the static context. The resulting absolute URI is promoted to an xs:string.

If the Available documents described in provides a mapping from this string to a document node, the function returns that document node.

The URI may include a fragment identifier.

By default, this function is deterministic. Two calls on this function return the same document node if the same URI Reference (after resolution to an absolute URI Reference) is supplied to both calls. Thus, the following expression (if it does not raise an error) will always be true:

However, for performance reasons, implementations may provide a user option to evaluate the function without a guarantee of determinism. The manner in which any such option is provided is implementation-defined. If the user has not selected such an option, a call of the function must either return a deterministic result or must raise a dynamic error .

For detailed type semantics, see [Formal Semantics].

If two calls to this function supply different absolute URI References as arguments, the same document node may be returned if the implementation can determine that the two arguments refer to the same resource.

By defining the semantics of this function in terms of a string-to-document-node mapping in the dynamic context, the specification is acknowledging that the results of this function are outside the purview of the language specification itself, and depend entirely on the run-time environment in which the expression is evaluated. This run-time environment includes not only an unpredictable collection of resources ("the web"), but configurable machinery for locating resources and turning their contents into document nodes within the XPath data model. Both the set of resources that are reachable, and the mechanisms by which those resources are parsed and validated, are .

One possible processing model for this function is as follows. The resource identified by the URI Reference is retrieved. If the resource cannot be retrieved, a dynamic error is raised . The data resulting from the retrieval action is then parsed as an XML document and a tree is constructed in accordance with the . If the top-level media type is known and is "text", the content is parsed in the same way as if the media type were text/xml; otherwise, it is parsed in the same way as if the media type were application/xml. If the contents cannot be parsed successfully, a dynamic error is raised . Otherwise, the result of the function is the document node at the root of the resulting tree. This tree is then optionally validated against a schema.

Various aspects of this processing are . Implementations may provide external configuration options that allow any aspect of the processing to be controlled by the user. In particular:

A dynamic error may be raised if $uri is not a valid URI.

A dynamic error is raised if the available documents provides no mapping for the absolutized URI.

A dynamic error is raised if the resource cannot be retrieved or cannot be parsed successfully as XML.

A dynamic error is raised if the implementation is not able to guarantee that the result of the function will be deterministic, and the user has not indicated that an unstable result is acceptable.

Returns the URI of a resource where a document can be found, if available.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If $arg is the empty sequence, the function returns the empty sequence.

If $arg is not a document node, the function returns the empty sequence.

Otherwise, the function returns the value of the document-uri accessor applied to $arg, as defined in (See ).

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the URI of a resource where a document can be found, if available.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If $arg is the empty sequence, the function returns the empty sequence.

If $arg is not a document node, the function returns the empty sequence.

Otherwise, the function returns the value of the document-uri accessor applied to $arg, as defined in (See ).

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the sequence of element nodes that have an ID value matching the value of one or more of the IDREF values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

Returns the sequence of element nodes that have an ID value matching the value of one or more of the IDREF values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

Returns true if the argument is the empty sequence.

This function is deterministic, context-independent, and focus-independent.

If the value of $arg is the empty sequence, the function returns true; otherwise, the function returns false.

The expression fn:empty((1,2,3)[10]) returns true().

The expression fn:empty(fn:remove(("hello", "world"), 1)) returns false().

Encodes reserved characters in a string that is intended to be used in the path segment of a URI.

This function is deterministic, context-independent, and focus-independent.

If $uri-part is the empty sequence, the function returns the zero-length string.

This function applies the URI escaping rules defined in section 2 of to the xs:string supplied as $uri-part. The effect of the function is to escape reserved characters. Each such character in the string is replaced with its percent-encoded form as described in .

Since recommends that, for consistency, URI producers and normalizers should use uppercase hexadecimal digits for all percent-encodings, this function must always generate hexadecimal values using the upper-case letters A-F.

All characters are escaped except those identified as "unreserved" by , that is the upper- and lower-case letters A-Z, the digits 0-9, HYPHEN-MINUS ("-"), LOW LINE ("_"), FULL STOP ".", and TILDE "~".

This function escapes URI delimiters and therefore cannot be used indiscriminately to encode "invalid" characters in a path segment.

This function is invertible but not idempotent. This is because a string containing a percent character will be modified by applying the function: for example 100% becomes 100%25, while 100%25 becomes 100%2525.

Returns true if the string $arg1 contains $arg2 as a trailing substring, taking collations into account.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

If the value of $arg1 or $arg2 is the empty sequence, or contains only ignorable collation units, it is interpreted as the zero-length string.

If the value of $arg2 is the zero-length string, then the function returns true. If the value of $arg1 is the zero-length string and the value of $arg2 is not the zero-length string, then the function returns false.

The collation used by this function is determined according to the rules in .

The function returns an xs:boolean indicating whether or not the value of $arg1 starts with a sequence of collation units that provides a match to the collation units of $arg2 according to the collation that is used.

A dynamic error may be raised if the specified collation does not support collation units.

Returns true if the string $arg1 contains $arg2 as a trailing substring, taking collations into account.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri.

If the value of $arg1 or $arg2 is the empty sequence, or contains only ignorable collation units, it is interpreted as the zero-length string.

If the value of $arg2 is the zero-length string, then the function returns true. If the value of $arg1 is the zero-length string and the value of $arg2 is not the zero-length string, then the function returns false.

The collation used by this function is determined according to the rules in .

The function returns an xs:boolean indicating whether or not the value of $arg1 starts with a sequence of collation units that provides a match to the collation units of $arg2 according to the collation that is used.

A dynamic error may be raised if the specified collation does not support collation units.

Returns the value of a system environment variable, if it exists.

This function is deterministic, context-dependent, and focus-independent. It depends on environment variables.

The set of available environment variables is a set of (name, value) pairs forming part of the dynamic context, in which the name is unique within the set of pairs. The name and value are arbitrary strings.

If the $name argument matches the name of one of these pairs, the function returns the corresponding value.

If there is no environment variable with a matching name, the function returns the empty sequence.

The collation used for matching names is , but must be the same as the collation used to ensure that the names of all environment variables are unique.

The function is deterministic, which means that if it is called several times within the same execution scope, with the same arguments, it must return the same result.

On many platforms, the term "environment variable" has a natural meaning in terms of facilities provided by the operating system. This interpretation of the concept does not exclude other interpretations, such as a mapping to a set of configuration parameters in a database system.

Environment variable names are usually case sensitive. Names are usually of the form (letter|_) (letter|_|digit)*, but this varies by platform.

On some platforms, there may sometimes be multiple environment variables with the same name; in this case, it is implementation-dependent as to which is returned; see for example (Chapter 8, Environment Variables). Implementations may use prefixes or other naming conventions to disambiguate the names.

The requirement to ensure that the function is deterministic means in practice that the implementation must make a snapshot of the environment variables at some time during execution, and return values obtained from this snapshot, rather than using live values that are subject to change at any time.

Operating system environment variables may be associated with a particular process, while queries and stylesheets may execute across multiple processes (or multiple machines). In such circumstances implementations may choose to provide access to the environment variables associated with the process in which the query or stylesheet processing was initiated.

Security advice: Queries from untrusted sources should not be permitted unrestricted access to environment variables. For example, the name of the account under which the query is running may be useful information to a would-be intruder. An implementation may therefore choose to restrict access to the environment, or may provide a facility to make fn:environment-variable always return the empty sequence.

Returns the value of a system environment variable, if it exists.

This function is deterministic, context-dependent, and focus-independent. It depends on environment variables.

The set of available environment variables is a set of (name, value) pairs forming part of the dynamic context, in which the name is unique within the set of pairs. The name and value are arbitrary strings.

If the $name argument matches the name of one of these pairs, the function returns the corresponding value.

If there is no environment variable with a matching name, the function returns the empty sequence.

The collation used for matching names is , but must be the same as the collation used to ensure that the names of all environment variables are unique.

The function is deterministic, which means that if it is called several times within the same execution scope, with the same arguments, it must return the same result.

On many platforms, the term "environment variable" has a natural meaning in terms of facilities provided by the operating system. This interpretation of the concept does not exclude other interpretations, such as a mapping to a set of configuration parameters in a database system.

Environment variable names are usually case sensitive. Names are usually of the form (letter|_) (letter|_|digit)*, but this varies by platform.

On some platforms, there may sometimes be multiple environment variables with the same name; in this case, it is implementation-dependent as to which is returned; see for example (Chapter 8, Environment Variables). Implementations may use prefixes or other naming conventions to disambiguate the names.

The requirement to ensure that the function is deterministic means in practice that the implementation must make a snapshot of the environment variables at some time during execution, and return values obtained from this snapshot, rather than using live values that are subject to change at any time.

Operating system environment variables may be associated with a particular process, while queries and stylesheets may execute across multiple processes (or multiple machines). In such circumstances implementations may choose to provide access to the environment variables associated with the process in which the query or stylesheet processing was initiated.

Security advice: Queries from untrusted sources should not be permitted unrestricted access to environment variables. For example, the name of the account under which the query is running may be useful information to a would-be intruder. An implementation may therefore choose to restrict access to the environment, or may provide a facility to make fn:environment-variable always return the empty sequence.

Calling the fn:error function raises an application-defined error.

This function is nondeterministic, context-independent, and focus-independent.

This function never returns a value. Instead it always raises an error. The effect of the error is identical to the effect of dynamic errors raised implicitly, for example when an incorrect argument is supplied to a function.

The parameters to the fn:error function supply information that is associated with the error condition and that is made available to a caller that asks for information about the error. The error may be caught either by the host language (using a try/catch construct in XSLT or XQuery, for example), or by the calling application or external processing environment. The way in which error information is returned to the external processing environment is

If fn:error is called with no arguments, then its behavior is the same as the function call:

If $code is the empty sequence then the effective value is the xs:QName constructed by:

There are three pieces of information that may be associated with an error:

This function always raises a dynamic error. By default, it raises

Calling the fn:error function raises an application-defined error.

This function is nondeterministic, context-independent, and focus-independent.

This function never returns a value. Instead it always raises an error. The effect of the error is identical to the effect of dynamic errors raised implicitly, for example when an incorrect argument is supplied to a function.

The parameters to the fn:error function supply information that is associated with the error condition and that is made available to a caller that asks for information about the error. The error may be caught either by the host language (using a try/catch construct in XSLT or XQuery, for example), or by the calling application or external processing environment. The way in which error information is returned to the external processing environment is

If fn:error is called with no arguments, then its behavior is the same as the function call:

If $code is the empty sequence then the effective value is the xs:QName constructed by:

There are three pieces of information that may be associated with an error:

This function always raises a dynamic error. By default, it raises

Calling the fn:error function raises an application-defined error.

This function is nondeterministic, context-independent, and focus-independent.

This function never returns a value. Instead it always raises an error. The effect of the error is identical to the effect of dynamic errors raised implicitly, for example when an incorrect argument is supplied to a function.

The parameters to the fn:error function supply information that is associated with the error condition and that is made available to a caller that asks for information about the error. The error may be caught either by the host language (using a try/catch construct in XSLT or XQuery, for example), or by the calling application or external processing environment. The way in which error information is returned to the external processing environment is

If fn:error is called with no arguments, then its behavior is the same as the function call:

If $code is the empty sequence then the effective value is the xs:QName constructed by:

There are three pieces of information that may be associated with an error:

This function always raises a dynamic error. By default, it raises

Calling the fn:error function raises an application-defined error.

This function is nondeterministic, context-independent, and focus-independent.

This function never returns a value. Instead it always raises an error. The effect of the error is identical to the effect of dynamic errors raised implicitly, for example when an incorrect argument is supplied to a function.

The parameters to the fn:error function supply information that is associated with the error condition and that is made available to a caller that asks for information about the error. The error may be caught either by the host language (using a try/catch construct in XSLT or XQuery, for example), or by the calling application or external processing environment. The way in which error information is returned to the external processing environment is

If fn:error is called with no arguments, then its behavior is the same as the function call:

If $code is the empty sequence then the effective value is the xs:QName constructed by:

There are three pieces of information that may be associated with an error:

This function always raises a dynamic error. By default, it raises

Escapes a URI in the same way that HTML user agents handle attribute values expected to contain URIs.

This function is deterministic, context-independent, and focus-independent.

If $uri is the empty sequence, the function returns the zero-length string.

Otherwise, the function escapes all characters except printable characters of the US-ASCII coded character set, specifically the codepoints between 32 and 126 (decimal) inclusive. Each character in $uri to be escaped is replaced by an escape sequence, which is formed by encoding the character as a sequence of octets in UTF-8, and then representing each of these octets in the form %HH, where HH is the hexadecimal representation of the octet. This function must always generate hexadecimal values using the upper-case letters A-F.

The behavior of this function corresponds to the recommended handling of non-ASCII characters in URI attribute values as described in Appendix B.2.1.

Returns $arg if it contains exactly one item. Otherwise, raises an error.

This function is deterministic, context-independent, and focus-independent.

Except in error cases, the function returns $arg unchanged.

For detailed type semantics, see [Formal Semantics].

A dynamic error is raised if $arg is an empty sequence or a sequence containing more than one item.

Returns true if the argument is a non-empty sequence.

This function is deterministic, context-independent, and focus-independent.

If the value of $arg is a non-empty sequence, the function returns true; otherwise, the function returns false.

The expression fn:exists(fn:remove(("hello"), 1)) returns false().

The expression fn:exists(fn:remove(("hello", "world"), 1)) returns true().

Returns the xs:boolean value false.

This function is deterministic, context-independent, and focus-independent.

The result is equivalent to xs:boolean("0").

The expression fn:false() returns xs:boolean(0).

Returns those items from the sequence $seq for which the supplied function $f returns true.

This function is deterministic, context-independent, and focus-independent.

The effect of the function is equivalent to the following implementation in XQuery:

or its equivalent in XSLT:

As a consequence of the function signature and the function calling rules, a type error occurs if the supplied function $f returns anything other than a single xs:boolean item; there is no conversion to an effective boolean value.

Rounds $arg downwards to a whole number.

This function is deterministic, context-independent, and focus-independent.

General rules: see .

The function returns the largest (closest to positive infinity) number with no fractional part that is not greater than the value of $arg.

If the type of $arg is one of the four numeric types xs:float, xs:double, xs:decimal or xs:integer the type of the result is the same as the type of $arg. If the type of $arg is a type derived from one of the numeric types, the result is an instance of the base numeric type.

For xs:float and xs:double arguments, if the argument is positive zero, then positive zero is returned. If the argument is negative zero, then negative zero is returned.

For detailed type semantics, see [Formal Semantics].

The expression fn:floor(10.5) returns 10.

The expression fn:floor(-10.5) returns -11.

Processes the supplied sequence from left to right, applying the supplied function repeatedly to each item in turn, together with an accumulated result value.

This function is deterministic, context-independent, and focus-independent.

The effect of the function is equivalent to the following implementation in XQuery:

or its equivalent in XSLT:

As a consequence of the function signature and the function calling rules, a type error occurs if the supplied function $f cannot be applied to two arguments, where the first argument is either the value of $zero or the result of a previous application of $f, and the second is $seq or any trailing subsequence of $seq.

Processes the supplied sequence from right to left, applying the supplied function repeatedly to each item in turn, together with an accumulated result value.

This function is deterministic, context-independent, and focus-independent.

The effect of the function is equivalent to the following implementation in XQuery:

or its equivalent in XSLT:

As a consequence of the function signature and the function calling rules, a type error occurs if the supplied function $f cannot be applied to two arguments, where the first argument is any item in the sequence $seq, and the second is either the value of $zero or the result of a previous application of $f.

Applies the function item $f to successive pairs of items taken one from $seq1 and one from $seq2, returning the concatenation of the resulting sequences in order.

This function is deterministic, context-independent, and focus-independent.

The effect of the function is equivalent to the following implementation in XQuery:

or its equivalent in XSLT:

The expression fn:for-each-pair(("a", "b", "c"), ("x", "y", "z"), concat#2) returns ("ax", "by", "cz").

The expression fn:for-each-pair(1 to 5, 1 to 5, function($a, $b){10*$a + $b} returns (11, 22, 33, 44, 55).

Applies the function item $f to every item from the sequence $seq in turn, returning the concatenation of the resulting sequences in order.

This function is deterministic, context-independent, and focus-independent.

The effect of the function is equivalent to the following implementation in XQuery:

or its equivalent in XSLT:

The function call fn:for-each($SEQ, $F) is equivalent to the expression for $i in $SEQ return $F($i), assuming that ordering mode is ordered.

Returns a string containing an xs:date value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Returns a string containing an xs:date value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Returns a string containing an xs:dateTime value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Returns a string containing an xs:dateTime value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Formats an integer according to a given picture string, using the conventions of a given natural language if specified.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default language.

The three-argument form of this function is deterministic, context-independent, and focus-independent.

If $value is an empty sequence, the function returns a zero-length string.

In all other cases, the $picture argument describes the format in which $value is output.

The rules that follow describe how non-negative numbers are output. If the value of $value is negative, the rules below are applied to the absolute value of $value, and a minus sign is prepended to the result.

The value of $picture consists of a primary format token, optionally followed by a format modifier. The primary format token is always present and must not be zero-length. If the string contains one or more semicolons then everything that precedes the last semicolon is taken as the primary format token and everything that follows is taken as the format modifier; if the string contains no semicolon then the entire picture is taken as the primary format token, and the format modifier is taken to be absent (which is equivalent to supplying a zero-length string).

The primary format token is classified as one of the following:

For all format tokens other than the first kind above (one that consists of decimal digits), there may be implementation-defined lower and upper bounds on the range of numbers that can be formatted using this format token; indeed, for some numbering sequences there may be intrinsic limits. For example, the format token ① (circled digit one, ①) has a range imposed by the Unicode character repertoire — 1 to 20 in Unicode versions prior to 4.0, increased in subsequent versions. For the numbering sequences described above any upper bound imposed by the implementation must not be less than 1000 (one thousand) and any lower bound must not be greater than 1. Numbers that fall outside this range must be formatted using the format token 1.

The above expansions of numbering sequences for format tokens such as a and i are indicative but not prescriptive. There are various conventions in use for how alphabetic sequences continue when the alphabet is exhausted, and differing conventions for how roman numerals are written (for example, IV versus IIII as the representation of the number 4). Sometimes alphabetic sequences are used that omit letters such as i and o. This specification does not prescribe the detail of any sequence other than those sequences consisting entirely of decimal digits.

Many numbering sequences are language-sensitive. This applies especially to the sequence selected by the tokens w, W and Ww. It also applies to other sequences, for example different languages using the Cyrillic alphabet use different sequences of characters, each starting with the letter #x410 (Cyrillic capital letter A). In such cases, the $lang argument specifies which language's conventions are to be used. If the argument is specified, the value should be either an empty sequence or a value that would be valid for the xml:lang attribute (see ). Note that this permits the identification of sublanguages based on country codes (from ISO 3166-1) as well as identification of dialects and regions within a country..

The set of languages for which numbering is supported is . If the $lang argument is absent, or is set to an empty sequence, or is invalid, or is not a language supported by the implementation, then the number is formatted using the default language from the dynamic context.

The format modifier must be a string that matches the regular expression ^([co](\(.+\))?)?[at]?$. That is, if it is present it must consist of one or more of the following, in any order:

If the o modifier is present, this indicates a request to output ordinal numbers rather than cardinal numbers. For example, in English, when used with the format token 1, this outputs the sequence 1st 2nd 3rd 4th ..., and when used with the format token w outputs the sequence first second third fourth ....

The string of characters between the parentheses, if present, is used to select between other possible variations of cardinal or ordinal numbering sequences. The interpretation of this string is implementation-defined. No error occurs if the implementation does not define any interpretation for the defined string.

For example, in some languages, ordinal numbers vary depending on the grammatical context: they may have different genders and may decline with the noun that they qualify. In such cases the string appearing in parentheses after the letter o may be used to indicate the variation of the ordinal number required. The way in which the variation is indicated will depend on the conventions of the language. For inflected languages that vary the ending of the word, the recommended approach is to indicate the required ending, preceded by a hyphen: for example in German, appropriate values are o(-e), o(-er), o(-es), o(-en).

It is implementation-defined what combinations of values of the format token, the language, and the cardinal/ordinal modifier are supported. If ordinal numbering is not supported for the combination of the format token, the language, and the string appearing in parentheses, the request is ignored and cardinal numbers are generated instead.

The use of the a or t modifier disambiguates between numbering sequences that use letters. In many languages there are two commonly used numbering sequences that use letters. One numbering sequence assigns numeric values to letters in alphabetic sequence, and the other assigns numeric values to each letter in some other manner traditional in that language. In English, these would correspond to the numbering sequences specified by the format tokens a and i. In some languages, the first member of each sequence is the same, and so the format token alone would be ambiguous. In the absence of the a or t modifier, the default is implementation-defined.

A dynamic error is raised if the format token is invalid, that is, if it violates any mandatory rules (indicated by an emphasized must or required keyword in the above rules). For example, the error is raised if the primary format token contains a digit but does not match the required regular expression.

Formats an integer according to a given picture string, using the conventions of a given natural language if specified.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default language.

The three-argument form of this function is deterministic, context-independent, and focus-independent.

If $value is an empty sequence, the function returns a zero-length string.

In all other cases, the $picture argument describes the format in which $value is output.

The rules that follow describe how non-negative numbers are output. If the value of $value is negative, the rules below are applied to the absolute value of $value, and a minus sign is prepended to the result.

The value of $picture consists of a primary format token, optionally followed by a format modifier. The primary format token is always present and must not be zero-length. If the string contains one or more semicolons then everything that precedes the last semicolon is taken as the primary format token and everything that follows is taken as the format modifier; if the string contains no semicolon then the entire picture is taken as the primary format token, and the format modifier is taken to be absent (which is equivalent to supplying a zero-length string).

The primary format token is classified as one of the following:

For all format tokens other than the first kind above (one that consists of decimal digits), there may be implementation-defined lower and upper bounds on the range of numbers that can be formatted using this format token; indeed, for some numbering sequences there may be intrinsic limits. For example, the format token ① (circled digit one, ①) has a range imposed by the Unicode character repertoire — 1 to 20 in Unicode versions prior to 4.0, increased in subsequent versions. For the numbering sequences described above any upper bound imposed by the implementation must not be less than 1000 (one thousand) and any lower bound must not be greater than 1. Numbers that fall outside this range must be formatted using the format token 1.

The above expansions of numbering sequences for format tokens such as a and i are indicative but not prescriptive. There are various conventions in use for how alphabetic sequences continue when the alphabet is exhausted, and differing conventions for how roman numerals are written (for example, IV versus IIII as the representation of the number 4). Sometimes alphabetic sequences are used that omit letters such as i and o. This specification does not prescribe the detail of any sequence other than those sequences consisting entirely of decimal digits.

Many numbering sequences are language-sensitive. This applies especially to the sequence selected by the tokens w, W and Ww. It also applies to other sequences, for example different languages using the Cyrillic alphabet use different sequences of characters, each starting with the letter #x410 (Cyrillic capital letter A). In such cases, the $lang argument specifies which language's conventions are to be used. If the argument is specified, the value should be either an empty sequence or a value that would be valid for the xml:lang attribute (see ). Note that this permits the identification of sublanguages based on country codes (from ISO 3166-1) as well as identification of dialects and regions within a country..

The set of languages for which numbering is supported is . If the $lang argument is absent, or is set to an empty sequence, or is invalid, or is not a language supported by the implementation, then the number is formatted using the default language from the dynamic context.

The format modifier must be a string that matches the regular expression ^([co](\(.+\))?)?[at]?$. That is, if it is present it must consist of one or more of the following, in any order:

If the o modifier is present, this indicates a request to output ordinal numbers rather than cardinal numbers. For example, in English, when used with the format token 1, this outputs the sequence 1st 2nd 3rd 4th ..., and when used with the format token w outputs the sequence first second third fourth ....

The string of characters between the parentheses, if present, is used to select between other possible variations of cardinal or ordinal numbering sequences. The interpretation of this string is implementation-defined. No error occurs if the implementation does not define any interpretation for the defined string.

For example, in some languages, ordinal numbers vary depending on the grammatical context: they may have different genders and may decline with the noun that they qualify. In such cases the string appearing in parentheses after the letter o may be used to indicate the variation of the ordinal number required. The way in which the variation is indicated will depend on the conventions of the language. For inflected languages that vary the ending of the word, the recommended approach is to indicate the required ending, preceded by a hyphen: for example in German, appropriate values are o(-e), o(-er), o(-es), o(-en).

It is implementation-defined what combinations of values of the format token, the language, and the cardinal/ordinal modifier are supported. If ordinal numbering is not supported for the combination of the format token, the language, and the string appearing in parentheses, the request is ignored and cardinal numbers are generated instead.

The use of the a or t modifier disambiguates between numbering sequences that use letters. In many languages there are two commonly used numbering sequences that use letters. One numbering sequence assigns numeric values to letters in alphabetic sequence, and the other assigns numeric values to each letter in some other manner traditional in that language. In English, these would correspond to the numbering sequences specified by the format tokens a and i. In some languages, the first member of each sequence is the same, and so the format token alone would be ambiguous. In the absence of the a or t modifier, the default is implementation-defined.

A dynamic error is raised if the format token is invalid, that is, if it violates any mandatory rules (indicated by an emphasized must or required keyword in the above rules). For example, the error is raised if the primary format token contains a digit but does not match the required regular expression.

Returns a string containing a number formatted according to a given picture string, taking account of decimal formats specified in the static context.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on decimal formats, and namespaces.

The effect of the two-argument form of the function is equivalent to calling the three-argument form with an empty sequence as the value of the third argument.

The function formats $value as a string using the picture string specified by the $picture argument and the decimal-format named by the $decimal-format-name argument, or the default decimal-format, if there is no $decimal-format-name argument. The syntax of the picture string is described in .

The $value argument may be of any numeric data type (xs:double, xs:float, xs:decimal, or their subtypes including xs:integer). Note that if an xs:decimal is supplied, it is not automatically promoted to an xs:double, as such promotion can involve a loss of precision.

If the supplied value of the $value argument is an empty sequence, the function behaves as if the supplied value were the xs:double value NaN.

The value of $decimal-format-name, if present and non-empty, must be a string which after removal of leading and trailing whitespace is in the form of an an EQName as defined in the XPath 3.0 grammar, that is one of the following:

The decimal format that is used is the decimal format in the static context whose name matches $decimal-format-name if supplied, or the default decimal format in the static context otherwise.

The evaluation of the format-number function takes place in two phases, an analysis phase described in and a formatting phase described in .

The analysis phase takes as its inputs the picture string and the variables derived from the relevant decimal format in the static context, and produces as its output a number of variables with defined values. The formatting phase takes as its inputs the number to be formatted and the variables produced by the analysis phase, and produces as its output a string containing a formatted representation of the number.

The result of the function is the formatted string representation of the supplied number.

A dynamic error is raised if the name specified as the $decimal-format-name argument is neither a valid lexical QName nor a valid URIQualifiedName, or if it uses a prefix that is not found in the statically known namespaces, or if the static context does not contain a declaration of a decimal-format with a matching expanded QName. If the processor is able to detect the error statically (for example, when the argument is supplied as a string literal), then the processor may optionally signal this as a static error.

Returns a string containing a number formatted according to a given picture string, taking account of decimal formats specified in the static context.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on decimal formats, and namespaces.

The effect of the two-argument form of the function is equivalent to calling the three-argument form with an empty sequence as the value of the third argument.

The function formats $value as a string using the picture string specified by the $picture argument and the decimal-format named by the $decimal-format-name argument, or the default decimal-format, if there is no $decimal-format-name argument. The syntax of the picture string is described in .

The $value argument may be of any numeric data type (xs:double, xs:float, xs:decimal, or their subtypes including xs:integer). Note that if an xs:decimal is supplied, it is not automatically promoted to an xs:double, as such promotion can involve a loss of precision.

If the supplied value of the $value argument is an empty sequence, the function behaves as if the supplied value were the xs:double value NaN.

The value of $decimal-format-name, if present and non-empty, must be a string which after removal of leading and trailing whitespace is in the form of an an EQName as defined in the XPath 3.0 grammar, that is one of the following:

The decimal format that is used is the decimal format in the static context whose name matches $decimal-format-name if supplied, or the default decimal format in the static context otherwise.

The evaluation of the format-number function takes place in two phases, an analysis phase described in and a formatting phase described in .

The analysis phase takes as its inputs the picture string and the variables derived from the relevant decimal format in the static context, and produces as its output a number of variables with defined values. The formatting phase takes as its inputs the number to be formatted and the variables produced by the analysis phase, and produces as its output a string containing a formatted representation of the number.

The result of the function is the formatted string representation of the supplied number.

A dynamic error is raised if the name specified as the $decimal-format-name argument is neither a valid lexical QName nor a valid URIQualifiedName, or if it uses a prefix that is not found in the statically known namespaces, or if the static context does not contain a declaration of a decimal-format with a matching expanded QName. If the processor is able to detect the error statically (for example, when the argument is supplied as a string literal), then the processor may optionally signal this as a static error.

Returns a string containing an xs:time value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Returns a string containing an xs:time value formatted for display.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on default calendar, and default language, and default place, and implicit timezone.

The five-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone, and namespaces.

See .

Returns the arity of the function identified by a function item.

This function is deterministic, context-independent, and focus-independent.

The fn:function-arity function returns the arity (number of arguments) of the function identified by $func.

The expression fn:function-arity(fn:substring#2) returns 2.

The expression fn:function-arity(function($node){name($node)}) returns 1.

The expression let $initial := fn:substring(?, 1, 1) return fn:function-arity($initial) returns 1.

This function returns a string that uniquely identifies a given node.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If the argument is the empty sequence, the result is the zero-length string.

In other cases, the function returns a string that uniquely identifies a given node.

The returned identifier must consist of ASCII alphanumeric characters and must start with an alphabetic character. Thus, the string is syntactically an XML name.

An implementation is free to generate an identifier in any convenient way provided that it always generates the same identifier for the same node and that different identifiers are always generated from different nodes. An implementation is under no obligation to generate the same identifiers each time a document is transformed or queried.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

This function returns a string that uniquely identifies a given node.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If the argument is the empty sequence, the result is the zero-length string.

In other cases, the function returns a string that uniquely identifies a given node.

The returned identifier must consist of ASCII alphanumeric characters and must start with an alphabetic character. Thus, the string is syntactically an XML name.

An implementation is free to generate an identifier in any convenient way provided that it always generates the same identifier for the same node and that different identifiers are always generated from different nodes. An implementation is under no obligation to generate the same identifiers each time a document is transformed or queried.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns true if the supplied node has one or more child nodes (of any kind).

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

Provided that the supplied argument $node matches the expected type node()?, the result of the function call fn:has-children($node) is defined to be the same as the result of the expression fn:exists($node/child::node()).

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns true if the supplied node has one or more child nodes (of any kind).

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

Provided that the supplied argument $node matches the expected type node()?, the result of the function call fn:has-children($node) is defined to be the same as the result of the expression fn:exists($node/child::node()).

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the first item in a sequence.

This function is deterministic, context-independent, and focus-independent.

The function returns the value of the expression $arg[1]

If $arg is the empty sequence, the empty sequence is returned. Otherwise the first item in the sequence is returned.

Returns the number of hours in a duration.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence, the function returns the empty sequence.

Otherwise, the function returns an xs:integer representing the hours component in the value of $arg. The result is obtained by casting $arg to an xs:dayTimeDuration (see ) and then computing the hours component as described in .

If $arg is a negative duration then the result will be negative..

If $arg is an xs:yearMonthDuration the function returns 0.

The expression fn:hours-from-duration(xs:dayTimeDuration("P3DT10H")) returns 10.

The expression fn:hours-from-duration(xs:dayTimeDuration("P3DT12H32M12S")) returns 12.

The expression fn:hours-from-duration(xs:dayTimeDuration("PT123H")) returns 3.

The expression fn:hours-from-duration(xs:dayTimeDuration("-P3DT10H")) returns -10.

Returns the hours component of an xs:time.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence, the function returns the empty sequence.

Otherwise, the function returns an xs:integer between 0 and 23, both inclusive, representing the value of the hours component in the local value of $arg.

Assume that the dynamic context provides an implicit timezone value of -05:00.

The expression fn:hours-from-time(xs:time("11:23:00")) returns 11.

The expression fn:hours-from-time(xs:time("21:23:00")) returns 21.

The expression fn:hours-from-time(xs:time("01:23:00+05:00")) returns 1.

The expression fn:hours-from-time(fn:adjust-time-to-timezone(xs:time("01:23:00+05:00"), xs:dayTimeDuration("PT0S"))) returns 20.

The expression fn:hours-from-time(xs:time("24:00:00")) returns 0.

Returns the sequence of element nodes that have an ID value matching the value of one or more of the IDREF values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The function returns a sequence, in document order with duplicates eliminated, containing every element node E that satisfies all the following conditions:

A dynamic error is raised if $node, or the context item if the second argument is absent, is a node in a tree whose root is not a document node.

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the sequence of element nodes that have an ID value matching the value of one or more of the IDREF values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The function returns a sequence, in document order with duplicates eliminated, containing every element node E that satisfies all the following conditions:

A dynamic error is raised if $node, or the context item if the second argument is absent, is a node in a tree whose root is not a document node.

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the sequence of element or attribute nodes with an IDREF value matching the value of one or more of the ID values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The function returns a sequence, in document order with duplicates eliminated, containing every element or attribute node $N that satisfies all the following conditions:

A dynamic error is raised if $node, or the context item if the second argument is omitted, is a node in a tree whose root is not a document node.

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the sequence of element or attribute nodes with an IDREF value matching the value of one or more of the ID values supplied in $arg.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The function returns a sequence, in document order with duplicates eliminated, containing every element or attribute node $N that satisfies all the following conditions:

A dynamic error is raised if $node, or the context item if the second argument is omitted, is a node in a tree whose root is not a document node.

The following errors may be raised when $node is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the value of the implicit timezone property from the dynamic context.

This function is deterministic, context-dependent, and focus-independent. It depends on implicit timezone.

Returns the value of the implicit timezone property from the dynamic context. Components of the dynamic context are discussed in .

Returns the prefixes of the in-scope namespaces for an element node.

This function is deterministic, context-independent, and focus-independent.

The function returns a sequence of strings representing the prefixes of the in-scope namespaces for $element.

For namespace bindings that have a prefix, the function returns the prefix as an xs:NCName. For the default namespace, which has no prefix, it returns the zero-length string.

The result sequence contains no duplicates.

The ordering of the result sequence is implementation-dependent.

Returns a sequence of positive integers giving the positions within the sequence $seq of items that are equal to $search.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The function returns a sequence of positive integers giving the positions within the sequence $seq of items that are equal to $search.

The collation used by this function is determined according to the rules in . This collation is used when string comparison is required.

The items in the sequence $seq are compared with $search under the rules for the eq operator. Values of type xs:untypedAtomic are compared as if they were of type xs:string. Values that cannot be compared, because the eq operator is not defined for their types, are considered to be distinct. If an item compares equal, then the position of that item in the sequence $seq is included in the result.

The first item in a sequence is at position 1, not position 0.

The result sequence is in ascending numeric order.

If the value of $seq is the empty sequence, or if no item in $seq matches $search, then the function returns the empty sequence.

No error occurs if non-comparable values are encountered. So when comparing two atomic values, the effective boolean value of fn:index-of($a, $b) is true if $a and $b are equal, false if they are not equal or not comparable.

Returns a sequence of positive integers giving the positions within the sequence $seq of items that are equal to $search.

The two-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and implicit timezone.

The three-argument form of this function is deterministic, context-dependent, and focus-independent. It depends on collations, and static base uri, and implicit timezone.

The function returns a sequence of positive integers giving the positions within the sequence $seq of items that are equal to $search.

The collation used by this function is determined according to the rules in . This collation is used when string comparison is required.

The items in the sequence $seq are compared with $search under the rules for the eq operator. Values of type xs:untypedAtomic are compared as if they were of type xs:string. Values that cannot be compared, because the eq operator is not defined for their types, are considered to be distinct. If an item compares equal, then the position of that item in the sequence $seq is included in the result.

The first item in a sequence is at position 1, not position 0.

The result sequence is in ascending numeric order.

If the value of $seq is the empty sequence, or if no item in $seq matches $search, then the function returns the empty sequence.

No error occurs if non-comparable values are encountered. So when comparing two atomic values, the effective boolean value of fn:index-of($a, $b) is true if $a and $b are equal, false if they are not equal or not comparable.

Returns every node within the input sequence that is not an ancestor of another member of the input sequence; the nodes are returned in document order with duplicates eliminated.

This function is deterministic, context-independent, and focus-independent.

The effect of the function call fn:innermost($nodes) is defined to be equivalent to the result of the expression $nodes except $nodes/ancestor::node().

That is, the function takes as input a sequence of nodes, and returns every node within the sequence that is not an ancestor of another node within the sequence; the nodes are returned in document order with duplicates eliminated.

If the source document contains nested sections represented by div elements, the expression innermost(//div) returns those div elements that do not contain further div elements.

Returns a sequence constructed by inserting an item or a sequence of items at a given position within an existing sequence.

This function is deterministic, context-independent, and focus-independent.

The value returned by the function consists of all items of $target whose index is less than $position, followed by all items of $inserts, followed by the remaining elements of $target, in that order.

For detailed type semantics, see [Formal Semantics].

If $target is the empty sequence, $inserts is returned. If $inserts is the empty sequence, $target is returned.

If $position is less than one (1), the first position, the effective value of $position is one (1). If $position is greater than the number of items in $target, then the effective value of $position is equal to the number of items in $target plus 1.

The value of $target is not affected by the sequence construction.

Converts a string containing an IRI into a URI according to the rules of .

This function is deterministic, context-independent, and focus-independent.

If $iri is the empty sequence, the function returns the zero-length string.

Otherwise, the function converts the value of $iri into a URI according to the rules given in Section 3.1 of by percent-encoding characters that are allowed in an IRI but not in a URI. If $iri contains a character that is invalid in an IRI, such as the space character (see note below), the invalid character is replaced by its percent-encoded form as described in before the conversion is performed.

Since recommends that, for consistency, URI producers and normalizers should use uppercase hexadecimal digits for all percent-encodings, this function must always generate hexadecimal values using the upper-case letters A-F.

The function is idempotent but not invertible. Both the inputs My Documents and My%20Documents will be converted to the output My%20Documents.

This function does not check whether $iri is a valid IRI. It treats it as an string and operates on the characters in the string.

The following printable ASCII characters are invalid in an IRI: "<", ">", " (double quote), space, "{", "}", "|", "\", "^", and "`". Since these characters should not appear in an IRI, if they do appear in $iri they will be percent-encoded. In addition, characters outside the range x20-x7E will be percent-encoded because they are invalid in a URI.

Since this function does not escape the PERCENT SIGN "%" and this character is not allowed in data within a URI, users wishing to convert character strings (such as file names) that include "%" to a URI should manually escape "%" by replacing it with "%25".

This function tests whether the language of $node, or the context item if the second argument is omitted, as specified by xml:lang attributes is the same as, or is a sublanguage of, the language specified by $testlang.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The behavior of the function if the second argument is omitted is exactly the same as if the context item (.) had been passed as the second argument.

The language of the argument $node, or the context item if the second argument is omitted, is determined by the value of the xml:lang attribute on the node, or, if the node has no such attribute, by the value of the xml:lang attribute on the nearest ancestor of the node that has an xml:lang attribute. If there is no such ancestor, then the function returns false.

If $testlang is the empty sequence it is interpreted as the zero-length string.

The relevant xml:lang attribute is determined by the value of the XPath expression:

If this expression returns an empty sequence, the function returns false.

Otherwise, the function returns true if and only if, based on a caseless default match as specified in section 3.13 of , either:

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

This function tests whether the language of $node, or the context item if the second argument is omitted, as specified by xml:lang attributes is the same as, or is a sublanguage of, the language specified by $testlang.

The one-argument form of this function is deterministic, context-dependent, and focus-dependent.

The two-argument form of this function is deterministic, context-independent, and focus-independent.

The behavior of the function if the second argument is omitted is exactly the same as if the context item (.) had been passed as the second argument.

The language of the argument $node, or the context item if the second argument is omitted, is determined by the value of the xml:lang attribute on the node, or, if the node has no such attribute, by the value of the xml:lang attribute on the nearest ancestor of the node that has an xml:lang attribute. If there is no such ancestor, then the function returns false.

If $testlang is the empty sequence it is interpreted as the zero-length string.

The relevant xml:lang attribute is determined by the value of the XPath expression:

If this expression returns an empty sequence, the function returns false.

Otherwise, the function returns true if and only if, based on a caseless default match as specified in section 3.13 of , either:

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the context size from the dynamic context.

This function is deterministic, context-dependent, and focus-dependent.

Returns the context size from the dynamic context. (See .)

A dynamic error is raised if the context item is absent.

Returns the local part of the supplied QName.

This function is deterministic, context-independent, and focus-independent.

If $arg is the empty sequence the function returns the empty sequence.

Otherwise, the function returns an xs:NCName representing the local part of $arg.

The expression fn:local-name-from-QName(fn:QName("http://www.example.com/example", "person")) returns "person".

Returns the local part of the name of $arg as an xs:string that is either the zero-length string, or has the lexical form of an xs:NCName.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If the argument is supplied and is the empty sequence, the function returns the zero-length string.

If the node identified by $arg has no name (that is, if it is a document node, a comment, a text node, or a namespace node having no name), the function returns the zero-length string.

Otherwise, the function returns the local part of the expanded-QName of the node identified by $arg, as determined by the dm:node-name accessor defined in ). This will be an xs:string whose lexical form is an xs:NCName.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Returns the local part of the name of $arg as an xs:string that is either the zero-length string, or has the lexical form of an xs:NCName.

The zero-argument form of this function is deterministic, context-dependent, and focus-dependent.

The one-argument form of this function is deterministic, context-independent, and focus-independent.

If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.

If the argument is supplied and is the empty sequence, the function returns the zero-length string.

If the node identified by $arg has no name (that is, if it is a document node, a comment, a text node, or a namespace node having no name), the function returns the zero-length string.

Otherwise, the function returns the local part of the expanded-QName of the node identified by $arg, as determined by the dm:node-name accessor defined in ). This will be an xs:string whose lexical form is an xs:NCName.

The following errors may be raised when $arg is omitted:

• If the context item is absent, dynamic error

• If the context item is not a node, type error .

Converts a string to lower case.

This function is deterministic, context-independent, and focus-independent.

If the value of $arg is the empty sequence, the zero-length string is returned.

Otherwise, the function returns the value of $arg after translating every character to its lower-case correspondent as defined in the appropriate case mappings section in the Unicode standard . For versions of Unicode beginning with the 2.1.8 update, only locale-insensitive case mappings should be applied. Beginning with version 3.2.0 (and likely future versions) of Unicode, precise mappings are described in default case operations, which are full case mappings in the absence of tailoring for particular languages and environments. Every upper-case character that does not have a lower-case correspondent, as well as every lower-case character, is included in the returned value in its original form.

Case mappings may change the length of a string. In general, the fn:upper-case and fn:lower-case functions are not inverses of each other: fn:lower-case(fn:upper-case($arg)) is not guaranteed to return $arg, nor is fn:upper-case(fn:lower-case($arg)). The Latin small letter dotless i (as used in Turkish) is perhaps the most prominent lower-case letter which will not round-trip. The Latin capital letter i with dot above is the most prominent upper-case letter which will not round trip; there are others, such as Latin capital letter Sharp S (#1E9E) which is introduced in Unicode 5.1.

These functions may not always be linguistically appropriate (e.g. Turkish i without dot) or appropriate for the application (e.g. titlecase). In cases such as Turkish, a simple translation should be used first.

Because the function is not sensitive to locale, results will not always match user expectations. In Quebec, for example, the standard uppercase equivalent of "è" is "È", while in metropolitan France it is more commonly "E"; only one of these is supported by the functions as defined.

Many characters of class Ll lack uppercase equivalents in the Unicode case mapping tables; many characters of class Lu lack lowercase equivalents.

Returns true if the supplied string matches a given regular expression.

This function is deterministic, context-independent, and focus-independent.

The effect of calling the first version of this function (omitting the argument $flags) is the same as the effect of calling the second version with the $flags argument set to a zero-length string. Flags are defined in .

If $input is the empty sequence, it is interpreted as the zero-length string.

The function returns true if $input or some substring of $input matches the regular expression supplied as $pattern. Otherwise, the function returns false. The matching rules are influenced by the value of $flags if present.

A dynamic error is raised if the value of $pattern is invalid according to the rules described in .

A dynamic error is raised if the value of $flags is invalid according to the rules described in .

Returns true if the supplied string matches a given regular expression.

This function is deterministic, context-independent, and focus-independent.

The effect of calling the first version of this function (omitting the argument $flags) is the same as the effect of calling the second version with the $flags argument set to a zero-length string. Flags are defined in .

If $input is the empty sequence, it is interpreted as the zero-length string.

The function returns true if $input or some substring of $input matches the regular expression supplied as $pattern. Otherwise, the function returns false. The matching rules are influenced by the value of $flags if present.

A dynamic error is raised if the value of $pattern is invalid according to the rules described in .

A dynamic error is raised if the value of $flags is invalid according to the rules described in .