Back	Standard: http://www.w3.org/TR/xslt#element-namespace-alias

<namespace-alias> : stylesheet-prefix

Standard excerpt:

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.