If, in OGUR Settings, you place a check in Allow Group Admins to define Registration Codes for new group subscribers to moderated groups, then the following setting options will appear on the "Edit" page of each of your groups:

• Set registration codes to allow users to join this group?

Do you wish to enter registration codes that will allow new subscribers to bypass admin approval and join this group?

• Delete registration code after it is used?

Do you want to delete each individual registration code after it is used to successfully subscribe a user to the group?

• Registration codes for allowing users to subscribe to this group without admin approval

Specify here the registration codes which will allow users who enter them to subscribe to this moderated group without being manually approved by the group administrator. Structure your entries like this:

Code1,Code2,Code3

Each registration code separated by a comma. No spaces.

Do you wish to automatically assign a specific "registration code group role" to new subscribers to this group who use this registration code to subscribe to this group? The role is limited to this group. This role assignment can be be removed by the groups' admin(s)

See http://drupal.org/node/217229 for details.