Microsoft XML Core Services (MSXML) 5.0 for Microsoft Office - XML Schemas

Piece

An atom, either a normal character, a character class, or a parenthesized regular expression, possibly followed by a quantifier.

Syntax

piece :: = atom quantifier?

The following table shows valid pieces R and their set of strings L(R).

Valid pieces R for atoms S and non-negative integers n and m such that n<=m Set of strings L(R)
S All strings in L(S).
S? The empty string, and all strings in L(S).
S* All strings in L(S?) and all strings ST with S in L(S*) and T in L(S).

All concatenations of zero or more strings from L(S).

S+ All strings ST with S in L(S) and T in L(S*).

All concatenations of one or more strings from L(S).

S{n, m} All strings ST with S in L(S) and T in L(S{n-1, m-1}).

All sequences of at least n, and at most m, strings from L(S).

S{n} All strings in L(S{n,n}).

All sequences of exactly n strings from L(S).

S{n,} All strings in L(S{n}S*).

All sequences of exactly n strings from L(S).

S{0, m} All strings ST with S in L(S?) and T in L(S{0, m-1}).

All sequences of at most m, strings from L(S).

S{0,0} The set containing only the empty string.

See Also

XML Schema Regular Expressions | XML Schema Regular Expressions Reference Chart | Atom | Data Type Facets | Quantifier