If the box is checked, TextMangler will ignore most non-letter characters when analyzing the text for words. This might be useful if you have opened a file that is not text-only. Such files often have non-letter characters inserted as formatting information for a particular word processor. However, using this option is usually not as satisfactory as converting such a file to 'text only' (or 'export') from within a word processor.
If the box is not checked, all characters except spaces, tabs and returns will be considered when making the list of words found in the file.
