For those of you who are not aware of the TX, it is a project to add a great deal more variety to the terrains available in RA2/YR, particularly Snow, NewUrban, Desert and Lunar. You can check out some of the upcomming features at
http://project.cannis.net/?page=terrain as well as download the current version 1.3 that improves mainly Desert and NewUrban. The Poll in the C-Gen RA2/YR modding forum is related to how the TX should handle subterranean unit movement as it is controlled by the theatre terrain control files (iso*.ini files). Since this is of interest to the larger community you should come and have your say (C-Gen registration is required to post to the forum).