XSL reference documentation generated from the W3C Recommendation 16 November 1999

XSL element namespace-alias

Literal Result Elements

In a template, an element in the stylesheet that does not belong to the XSLT namespace and that is not an extension element (see extension-element) is instantiated to create an element node with the same expanded-name. The content of the element is a template, which is instantiated to give the content of the created element node. The created element node will have the attribute nodes that were present on the element node in the stylesheet tree, other than attributes with names in the XSLT namespace.

The created element node will also have a copy of the namespace nodes that were present on the element node in the stylesheet tree with the exception of any namespace node whose string-value is the XSLT namespace URI (http://www.w3.org/1999/XSL/Transform), a namespace URI declared as an extension namespace (see extension-element), or a namespace URI designated as an excluded namespace. A namespace URI is designated as an excluded namespace by using an exclude-result-prefixes attribute on an xsl:stylesheet element or an xsl:exclude-result-prefixes attribute on a literal result element. The value of both these attributes is a whitespace-separated list of namespace prefixes. The namespace bound to each of the prefixes is designated as an excluded namespace. It is an error if there is no namespace bound to the prefix on the element bearing the exclude-result-prefixes or xsl:exclude-result-prefixes attribute. The default namespace (as declared by xmlns) may be designated as an excluded namespace by including #default in the list of namespace prefixes. The designation of a namespace as an excluded namespace is effective within the subtree of the stylesheet rooted at the element bearing the exclude-result-prefixes or xsl:exclude-result-prefixes attribute; a subtree rooted at an xsl:stylesheet element does not include any stylesheets imported or included by children of that xsl:stylesheet element.

Note: When a stylesheet uses a namespace declaration only for the purposes of addressing the source tree, specifying the prefix in the exclude-result-prefixes attribute will avoid superfluous namespace declarations in the result tree.

The value of an attribute of a literal result element is interpreted as an attribute value template: it can contain expressions contained in curly braces ({}).

A namespace URI in the stylesheet tree that is being used to specify a namespace URI in the result tree is called a literal namespace URI. This applies to:

the namespace URI in the expanded-name of a literal result element in the stylesheet
the namespace URI in the expanded-name of an attribute specified on a literal result element in the stylesheet
the string-value of a namespace node on a literal result element in the stylesheet

<namespace-alias>
stylesheet-prefix = prefix | #default
result-prefix = prefix | #default
Model: EMPTY
</namespace-alias>

A stylesheet can use the xsl:namespace-alias element to declare that one namespace URI is an alias for another namespace URI. When a literal namespace URI has been declared to be an alias for another namespace URI, then the namespace URI in the result tree will be the namespace URI that the literal namespace URI is an alias for, instead of the literal namespace URI itself. The xsl:namespace-alias element declares that the namespace URI bound to the prefix specified by the stylesheet-prefix attribute is an alias for the namespace URI bound to the prefix specified by the result-prefix attribute. Thus, the stylesheet-prefix attribute specifies the namespace URI that will appear in the stylesheet, and the result-prefix attribute specifies the corresponding namespace URI that will appear in the result tree. The default namespace (as declared by xmlns) may be specified by using #default instead of a prefix. If a namespace URI is declared to be an alias for multiple different namespace URIs, then the declaration with the highest import precedence is used. It is an error if there is more than one such declaration. An XSLT processor may signal the error; if it does not signal the error, it must recover by choosing, from amongst the declarations with the highest import precedence, the one that occurs last in the stylesheet.

When literal result elements are being used to create element, attribute, or namespace nodes that use the XSLT namespace URI, the stylesheet must use an alias. For example, the stylesheet

<xsl:stylesheet
  version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:fo="http://www.w3.org/1999/XSL/Format"
  xmlns:axsl="http://www.w3.org/1999/XSL/TransformAlias">

<xsl:namespace-alias stylesheet-prefix="axsl" result-prefix="xsl"/>

<xsl:template match="/">
  <axsl:stylesheet>
    <xsl:apply-templates/>
  </axsl:stylesheet>
</xsl:template>

<xsl:template match="block">
  <axsl:template match="{.}">
     <fo:block><axsl:apply-templates/></fo:block>
  </axsl:template>
</xsl:template>

</xsl:stylesheet>

will generate an XSLT stylesheet from a document of the form:

<elements>
<block>p</block>
<block>h1</block>
<block>h2</block>
<block>h3</block>
<block>h4</block>
</elements>

Note: It may be necessary also to use aliases for namespaces other than the XSLT namespace URI. For example, literal result elements belonging to a namespace dealing with digital signatures might cause XSLT stylesheets to be mishandled by general-purpose security software; using an alias for the namespace would avoid the possibility of such mishandling.