The official Rules of Dixonary were posted on CompuServe on 4 January 1990 by Anders Sterner. In the intervening twenty years a body of precedent has been built up which players are expected—somehow—to know. Much of this precedent is old; most of it refines on the rules; some of it downright contradicts them.
This does not bother long-standing players, who play by an internalized set of rules, some of which approximate the written ones, and some of which are based on the precedent, that—officially, anyway—goes unrecorded.
Which is why some long-standing players regard close attention to the written rules as an annoying distraction from the real game.
To a new arrival, Dixonary players seem like a band of scofflaws, applying the rules they like and ignoring the ones they don't, and generally making things up as they go along. But appearances can be deceptive, and the rules are in fact quite rigid. They just haven't been written down lately.
This is hard on new players. These 'real' rules are for them, especially when they have to deal for the first time, and conscientiously read the 1990 rules, only to discover they have been playing a rather different game. Despite these rules' being unofficial, you will not get into trouble if you play as if they were. That cannot be said for the 1990 rules: if you take those rules at literal face value you risk getting blasted for not knowing how the game is really played.
For players outside North America who want a hard copy, also available in A4 format.
There are also some commentaries on how the game works. These are not addressed to new players.