xsl:pattern 

A match pattern as defined in the XSLT 2.0 Recommendation.
The syntax for patterns is a restricted form of the syntax for
XPath 2.0 expressions.

Simple Type Information

Used By

Attributes xsl:for-each-group/@group-ending-with, xsl:for-each-group/@group-starting-with, xsl:key/@match, xsl:number/@count, xsl:number/@from, xsl:sequence-constructor-group/@match, xsl:template/@match

Source 

<xs:simpleType name="pattern">
  <xs:annotation>
    <xs:documentation>A match pattern as defined in the XSLT 2.0 Recommendation. The syntax for patterns is a restricted form of the syntax for XPath 2.0 expressions.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xsl:expression"/>
</xs:simpleType>