Narrowing the Character Set has two effects:

• It influences the automatic recognition module selection
• It may increase accuracy

The filtering system allows the Language environment to be narrowed by enabling only certain character classes, and also by enabling individual characters. A filter is built up from filter elements, as detailed under the enumIGRecChrFilter description.

Each filter element name tells which character class is enabled; e.g., IG_REC_FILTER_ALL means no filtering. Not all recognition modules interpret all filter elements. Precise information appears in the sub-heading for each module.

Applying a filter may not always enable the same number of characters; e.g., IG_REC_FILTER_MISCELLANEOUS can enable only those miscellaneous characters supported by the recognition module assigned to the zone.