The 1994 Star Wars Style guide imposed several restrictions on writers. Changing the power structure of the galaxy or introducing new technology was a no go. One of the biggest rules imposed in it (before the prequels came about and negated them) was "Do not talk about the past". Specifically, writers were barred from depicting anything that took place before A New Hope (i.e. the Clone Wars, specifics of the Old Republic, how the Emperor came to power, how the rebellion stole the X-Wing prototype, the fall of the Republic and the Jedi Knights, the history of the Emperor and Vader, the history of the Mandalorians, and anything about the history of the Jedi Knights). The lone exception to these were The Han Solo Trilogy, The Han Solo Adventures and The Lando Calrissian Adventures books, which are prequels to A New Hope and Empire Strikes Back whose publication precedes the mandate.
Under no circumstances were Luke Skywalker, Han Solo or Princess Leia to be killed off. The only works that got around this were either stories set in the far future and thus beyond the natural lifespans of the characters, or non-canon infinites stories.
Yoda's species and home planet were not to be named. Likewise there was a longtime ban on Darth Sidious childhood and apprenticeship to Darth Plagueis. The latter ban was eventually lifted with the publishing of Darth Plagueis.
Finally and most oddly, Wookiee Jedi and other Wookiee Force users were forbidden. This ban came a number of years into the series, so several Wookiees got around the restriction. An embargo on Hutt Jedi was instated as well.
Fan Nickname: Pelly (Pellaeon), Farmboy (Luke), and as meta examples, Talifan (Mandalorian haters/Karen Traviss detractors) and Fandalorian (Mandalorian fans).