The program works by preventing the user from accessing sites with certain keywords which Scientology has identified as being objectionable material for viewing by their members. This use of keywords functions as a way to prevent members from learning of guarded Scientology doctrine, such as Xenu, OT III, and other material relating to Space opera in Scientology scripture. Other keywords on notable topics which are blocked by the program include the names of several notable critics of Scientology, including Robert Vaughn Young and Keith Henson, as well as several hundred other frequent participants in the alt.religion.scientology newsgroup, together with terms like Suppressive Person, and Lisa McPherson.