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.
fn:idref( $arg as xs:string*node()*fn:idref( $arg as xs:string*,$node as node()node()* The function returns a sequence, in document order with duplicates eliminated,
containing every element or attribute node $N that satisfies all the
following conditions:
$N is in the target document. The target document is the document
containing $node or the document containing the context item
(.) if the second argument is omitted. The behavior of the
function if $node is omitted is exactly the same as if the context
item had been passed as $node.
$N has an IDREF value equal to one of the candidate
ID values, where:
A node $N has an IDREF value equal to
V if both of the following conditions are true:
The is-idrefs property (see ) of $N is true.
The sequence
fn:tokenize(fn:normalize-space(fn:string($N)), ' ')contains a string that is
equal to V under the rules of the eq
operator using the Unicode code point collation
(http://www.w3.org/2005/xpath-functions/collation/codepoint).
Each xs:string in $arg is parsed as if it were of
lexically of type xs:ID. These xs:strings are then
included in the list of candidate xs:IDs. If any of the strings
in $arg is not a lexically valid xs:ID (that is,
if it is not lexically an xs:NCName), it is ignored. More
formally, the candidate ID values are the strings in the
sequence:
let $emp :=
The expression $emp/(element-with-id('ID21256')/@xml:id => fn:idref())/ancestor::employee/last => string() returns "Brown".
The expression $emp/(element-with-id('E30561')/empnr => fn:idref())/ancestor::employee/last => string() returns "Singh".
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 .
An element or attribute typically acquires the is-idrefs property by being
validated against the schema type xs:IDREF or xs:IDREFS, or
(for attributes only) by being described as of type IDREF or
IDREFS in a DTD.
Because the function is sensitive to the way in which the data model is constructed, calls on this function are not always interoperable.
No error is raised in respect of a candidate ID value that does not match
the IDREF value of any element or attribute in the document. If no
candidate ID value matches the IDREF value of any element or
attribute, the function returns the empty sequence.
It is possible for two or more nodes to have an IDREF value that matches a
given candidate ID value. In this situation, the function will return all
such nodes. However, each matching node will be returned at most once, regardless how
many candidate ID values it matches.
It is possible in a well-formed but invalid document to have a node whose
is-idrefs property is true but that does not conform to the lexical
rules for the xs:IDREF type. The effect of the above rules is that
ill-formed candidate ID values and ill-formed IDREF values are
ignored.
If the data model is constructed from a PSVI, the typed value of a node that has the
is-idrefs property will contain at least one atomic value of type
xs:IDREF (or a type derived by restriction from xs:IDREF).
It may also contain atomic values of other types. These atomic values are treated as
candidate ID values if two conditions are met: their lexical form must be valid as an
xs:NCName, and there must be at least one instance of xs:IDREF
in the typed value of the node. If these conditions are not satisfied, such values are ignored.