This attribute may be set on most XSLT elements that have an as attribute (xsl:variable, xsl:param, xsl:with-param, xsl:function, xsl:template: but not currently xsl:accumulator) to declare an additional more specific type for a value.

For example:

<xsl:param name="options" as="map(xs:string, xs:anyAtomicType*)" saxon:as="tuple(validate: xs:boolean, duplicates: xs:boolean, limit: xs:integer, codes: xs:string*)" xmlns:saxon="" select="map{'validate': true(), 'duplicates': false(), 'limit': 17, 'codes': ('USD', 'GBP', 'EUR')}"/><xsl:variable name="sqlConnection" saxon:as="javatype:java.sql.Connection" xmlns:saxon="" xmlns:javatype="" select="..."/><xsl:param name="when" required="yes" as="xs:anyAtomicType" saxon:as="union(xs:date, xs:time, xs:dateTime)" xmlns:saxon="">

If both the as and saxon:as attributes are present, then the type given in the saxon:as attribute must be a subtype of the type given in the as attribute.

The saxon:as attribute will be ignored by a conformant XSLT processor that does not recognize the Saxon namespace. The attribute therefore allows type information to be specified for use by Saxon, which will be ignored by other XSLT processors (this applies to XSLT 1.0 and 2.0 processors as well as XSLT 3.0 processors). It therefore allows stylesheets to take advantage of Saxon extensions to the sequence type syntax (notably, tuple types, union types, and type aliases; see Syntax extensions) without sacrificing stylesheet portability.