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) *
Remarks
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
Reference
XML Schema Regular Expressions
XML Schema Regular Expressions Reference Chart
Branch