XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (595 page)

Usage

This function is often used in conjunction with
in-scope-prefixes()
, which finds the prefixes of all the in-scope namespaces for an element as a sequence of strings.

Note that if the requirement is to resolve a lexical QName to obtain an
xs:QName
value, the
resolve-QName()
function provides an easier way of doing this.

See Also

in-scope-prefixes()
on page 808

resolve-QName()
on page 804

namespace-uri-from-QName

The function
namespace-uri-from-QName()
returns the namespace URI part of an
xs:QName
value.

Signature

Effect

Given an expanded QName (that is, an instance of type
xs:QName
), this function returns the namespace URI part of the value. If the
xs:QName
is in no namespace, it returns a zero-length URI.

Examples

The second example assumes that the context node has an attribute called
xml:space
.

See Also

QName()
on page 858

local-name-from-QName()
on page 826

nilled

The
nilled()
function returns true if applied to an element that (a) specifies
xsi:nil=“true”
, and (b) has been successfully validated against a schema.

Signature

Effect

If the input is an element node that has the attribute
xsi:nil=“true”
and that has been subjected to schema validation, the function returns true.

If the input is an element node that does not have an
xsl:nil
attribute, or that has the value
xsi:nil=“false”
, or if it is an element node that has not been assessed against a schema, the function returns false.

The function returns the empty sequence if it is applied to a node other than an element, or if the argument is an empty sequence.

Examples

Assume the context node is the following element:

and that it is validated against the following schema:

Usage

The
xsi:nil
attribute is an explicit way of saying that a value is absent. Although its meaning is entirely up to the application, the intended purpose is to distinguish unknown data (a person's title is unknown) from data known to be empty (a person is known to have no middle name). When an element that has
xsi:nil
set to true is validated, it is given the
nilled
property in the data model, and this function allows this property to be tested. For most practical purposes, using the
nilled()
function achieves the same as testing the
xsi:nil
attribute directly, so long as you are sure that the element has been validated.

The
nilled
property is present in the data model primarily to support the rules for type matching: a
nilled
element will not match a type of the form
element(N
,
T)
, but it will match
element(N, T?)
. These rules are given in Chapter 11, in the section
Matching Elements and Attributes
on page 672. This function is provided to allow direct access to this property.