XML::RegExp – Regular expressions for XML tokens – Manual Page

       This package contains regular expressions for the following XML tokens: BaseChar, Ideographic, Letter,
       Digit, Extender, CombiningChar, NameChar, EntityRef, CharRef, Reference, Name, NmToken, and AttValue.

       The definitions of these tokens were taken from the XML spec (Extensible Markup Language 1.0) at
       <http://www.w3.org/TR/REC-xml>.

       Also contains the regular expressions for the following tokens from the XML Namespaces spec at
       <http://www.w3.org/TR/REC-xml-names>: NCNameChar, NCName, QName, Prefix and LocalPart.