Ok, finally I got it: http://www.w3.org/TR/REC-xml/#CharClasses You can see what those classes are here: Search for "General Category Escapes" http://www.webreference.com/programming/awxml1/6.html So this means more or less: + All Letters + All Marks + Digits + Characters ':' and '_' are allowed as name-start characters. + Characters '-' and '.' are allowed as name characters.
-- José Abílio
