Ratel

If you are using an Okapi Tool after the M9 release, you should be using the wiki online help:
http://www.opentag.com/okapi/wiki/index.php?title=Ratel

This dialog box allows you to edit the data of a language map.

Regular expression describing the language map -- Enter the regular expression matching the language or languages for the language rule (group of rules) of this language map.

Name of the language rule associated with the regular expression -- Enter the name of the language rule (group of rules) for this language map. The name is case-sensitive.