or download this
my $XML_BaseChar= qr/@{[ "[" . # a character class...
"\x{0041}-\x{005A}" . # the first range
"\x{0100}-\x{0131}\x{0134}-\x{013E}\x{0141}-\x{0148}" . # the next
+range
"\x{01FA}-\x{0217}\x{0250}-\x{02A8}" . # etc.
"]" ]}/; #here's how to close it up