NorthStar currently stores all the regular expressions used by the template system in the database. To add, modify or delete regular expressions you need to click the 'Manage Regex's' link on the leftmost frame of the NorthStar window. To access this interface make sure that you have all the relevant Regex permissions activated for that particular user. By default NorthStar comes with a basic set of regular expressions that should be fairly adequate for most uses.
To add a regular expression just click the 'Add Regex' link in the top right of the regex listing. On the form that loads fill out the values. The name field is a simple name for the regex. The example field is show to the user and is supposed to help them determine what this field can take as valid input. The regex field is the actual regular expression itself. You should test any new regex's independently before putting them into NorthStar because it does not currently check the syntax of entered regular expressions.
To edit a regex just click the 'Edit' link to the right of the regex name and then update the values to what you need them to be. After your done click the 'Update Regex' button to save your changes.
To delete a regex click the 'Delete' link to the right of the regex name. Please note that regex's may only be deleting if their are currently no fields using them.