Inside XSLT

The <xsl:namespace-alias> Element: Generating Stylesheets

One of the primary uses for XSLT is to transform stylesheets into other stylesheets, although that might not be obvious at first. For example, you might want to flesh out long rules that need to be customized just before processing documents. And as you know, XSLT was originally introduced to help create formatting object stylesheets in the first place.

However, this raises an issue: If you process a stylesheet full of elements such as <xsl:template> and <xsl:apply-templates>that you want to appear in the result document—because the result document is itself a stylesheet—how is XSLT to know how to differentiate those literal result elements from the XSLT elements it should be processing? ...