Extension instructions calling named templates

If the name of a named template uses a namespace listed in an extension-element-prefixes attribute, then a call on the named template may be written as an extension instruction, as an alternative to using xsl:call-template.

For example, if the template is declared as:

<xsl:template name="x:indent"> <xsl:param name="spaces" as="xs:integer"/> <xsl:value-of select="'
' || string-join((1 to $spaces)!' ')"/> </xsl:template>

Then it may be invoked by writing:

<x:indent spaces="4"/>

which (assuming the presence of extension-element-prefixes="x") is equivalent to:

<xsl:call-template name="x:indent"> <xsl:with-param name="spaces" select="4"/> </xsl:call-template>

Attributes on the extension instruction are mapped to parameters declared in the named template. The rules for passing parameters are as follows:

If the parameter is declared with as="xs:string" then the attribute is interpreted as an attribute value template.
If the parameter is declared with as="xs:boolean" then the attribute is interpreted as an attribute value template, accepting the values "0", "false", or "no" for false, or "1", "true", or "yes" for true.
In all other cases the value of the attribute is treated as an XPath expression, which must evaluate to a value of the required type (after any conversion, using the function conversion rules).

Parameters that may be omitted (and defaulted) in an xsl:call-template instruction may similarly be omitted in the extension instruction.

The extension instruction must have no children other than xsl:fallback.

There is no way to supply tunnel parameters.