Here is a passage from The Traveller Book (1982, p 123); it is found in a description of types of scenario/adventure:
The choreographed novel [my emphasis] involves a setting already thought out by the referee and presented to the players; it may be any of the above settings [ship, location or world], but contains predetermined elements. As such, the referee has already developed characters and setting which bear on the group's activities, and they are guided gently to the proper locations. Properly done, the players never know that the referee has manipulated them to a fore-ordained goal
The "gentle guidance" and "manipulation" referred to here are exactly instances of what gets labelled
GM force. The aspiration that the players not know about it, if it is "properly done", is exactly what gets labelled
illusionism. (It is consistent with illusionism that the players know, in general terms, that it is going on - eg it won't be spoiled by a player having read this passage in The Traveller Book. The aspiration for player ignorance is not in respect of the general phenomenon, but rather at the point of application of GM force.)
This passage has no equivalent in the 1977 version of Classic Traveller.