cityselect is a base Extra template that is useful when wanting to create a new Extra for MODx Revolution. One can git archive from this repository to start with all the file structure for beginning MODx Extra development pre-setup.
cityselect is distributed as GPL (as MODx Revolution is), but the copyright owner (Shaun McCormick) grants all users of cityselect the ability to modify, distribute and use cityselect in MODx development as they see fit, as long as attribution is given somewhere in the distributed source of all derivative works.