The main reason for using regular expressions is to either achieve higher recognition accuracy or to better detect errors. Regular expressions are implemented through the User Dictionaries of the Checking module. Each item or entry added to a User Dictionary (called a UDitem) must be classified as a literal string (typically a word) or as a regular expression. Using User Dictionary sections, UD-items can be applied on a per-zone basis.

A regular expression defines a permissible pattern of characters by specifying character classes, ranges, or individual characters to be valid for one or more character positions in a zone.

Regular expressions are usually used in form-like situations, where zone contents are short and in some way predictable.

This section provides information about the following:

• Using Regular Expressions in the User Dictionary
• Anatomy of a Regular Expression