When matching data it is usually advantageous to perform certain character normalizations before matching. These include things such as mapping all letters to a common letter case, normalizing white space, stripping out certain special characters. A character map defines the set of rules to be applied. ibi™ Patterns - Search has a default character map that is appropriate for most cases. It maps all letters to lower case, strips all diacritic marks from letters, maps all punctuation and special characters to a blank, maps all whitespace to blanks, and compresses out all repeated blanks. There is also a second predefined character map that is similar to the standard map except that punctuation and special characters are left unchanged. For those cases where neither of these are appropriate the user can define their own character mapping rules. This class is the means by which these character mapping rules are defined.

Terms such as "letter" and "whitespace" are as defined in the unicode standard. The exception is that "punctuation" or "special characters" is a little broader than the unicode standard. Within the ASCII range this includes all characters that are not letters, digits or whitespace.

The first 16 bits of the full unicode character set are supported. This includes all commonly used code pages, including the Chinese and Japanese characters.