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XQuery by Priscilla Walmsley

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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 ...

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