| Microsoft XML Core Services (MSXML) 5.0 for Microsoft Office - XML Schemas |  |
Regular Expression
A sequence of characters that denote a set of strings (also represented as L(R)). When used to constrain a lexical space, a regular expression asserts that only strings in the set of strings are valid literals for values of that type.
A regular expression is composed of zero or more branches that are separated by the "or" (|) character.
Syntax
regExp :: = branch ('|' branch) *
The following table shows valid regular expressions R and their set of strings L(R).
| Valid regular expressions R for all branches S and regular expressions T | Set of strings L(R) |
|---|---|
| (empty string) | The set containing only the empty string. |
| S | All strings in L(S). |
| S|T | All strings in L(S) and all strings in L(T). |
See Also
XML Schema Regular Expressions | XML Schema Regular Expressions Reference Chart | Branch | Data Type Facets