Star Trek maintains two layers of canon. Anything on screen (TV or movie) is “alpha canon.” Books, comics, games, etc. are “beta canon” and generally considered below the alpha class of information, but canon until contradicted by alpha canon or statements by creators. The most commonly cited and held in highest regard pieces of beta canon are the various tech manuals which have ven been used frequently by writers, but occasionally contradicted on screen.

See: Memory Alpha (shows, movies), vs. Memory Beta (that, plus everything else)