\w was the Perl word class (alphabetic, decimal, underscore). XSD 1.0 Datatypes
F.1 defines \w as [#x0000-#x10FFFF]-[\p{P}\p{Z}\p{C}], so symbols and marks are
word characters and the connector `_` (Pc) is not; \W is its complement and had
wrongly matched symbols. \w is now computed as "not punctuation, separator, or
other" via the category matcher.
XSTS: invalid instances accepted 231 to 210. The internal regex fixtures that
assumed `_` is a word character encoded Perl semantics and were corrected to the
XSD definition (symbols are word chars, `_` is not), confirmed against the XSTS
reV cases.
Refs #147, #129.