XQuery

Representing Groups of Characters

Sometimes characters fall into convenient groups, such as decimal digits or punctuation characters. Three different kinds of escapes can be used to represent a group of characters: multi-character escapes, category escapes, and block escapes. Like single-character escapes, they all start with a backslash.

Multi-Character Escapes

Multi-character escapes, listed in Table 18-7, represent groups of related characters. They are called multi-character escapes because they allow a choice of multiple characters. However, each escape represents only one character in a matching string. To allow several replacement characters, you should use a quantifier such as +.

Table 18-7. Multi-character escapes

Escape	Meaning
\s	A whitespace character, as defined by XML (space, tab, carriage return, or line feed)
\S	A character that is not a whitespace character
\d	A decimal digit (0 to 9), or a digit in another style, for example, an Indic Arabic digit
\D	A character that is not a decimal digit
\w	A "word" character, that is, any character not in one of the Unicode categories Punctuation, Separators, and Other
\W	A nonword character, that is, any character in one of the Unicode categories Punctuation, Separators, and Other
\i	A character that is allowed as the first character of an XML name, i.e., a letter, an underscore (_), or a colon (:); the "i" stands for "initial"
\I	A character that cannot be the first character ...