The xsl:namespace-alias element is a top-level element that is used to control the mapping
between a namespace URI used in the stylesheet and the corresponding namespace URI used in the result
document.
Normally when a literal result element is encountered in a template, the namespace used for the element name and attribute names in the result document is the same as the namespace used in the stylesheet. If a different namespace is wanted (e.g. because the result document is a stylesheet using the XSLT namespace), then xsl:namespace-alias can be used to define the mapping.
Example: This example allows the prefix outxsl to be used for output elements that are to be associated with the XSLT namespace. It assumes that both namespaces xsl and outxsl have been declared and are in scope.
<xsl:namespace-alias stylesheet-prefix="outxsl" result-prefix="xsl"/>