Regexp

http://www.w3.org/TR/xmlschema-2/#regexs A ·regular expression· R is a sequence of characters that denote a set of strings L(R). When used to constrain a ·lexical space·, a regular expression R asserts that only strings in L(R) are valid literals for values of that type. Note: Unlike some popular regular expression languages (including those defined by Perl and standard Unix utilities), the regu..