Before the game is started, the player hosting the particular Lexicon should set the general subject - being preferably vague, but giving enough guidance that the players don't start on nothing. "You are all scholars arguing about how the Void Ghost Rebellion led to the overthrow of the theocracy and the establishment of the Third Republic." What that theocracy entailed, or what happened to the first two republics, or what the Void Ghost Rebellion is, are all unknown - they are named specifically to evoke a mood and inspire the other players' creativity.
The host should decide how many days each turn should be, and what the indices are. Each index comprises one turn, so for standard Lexicon Game playing with one index for each letter of the alphabet, there would be 26 turns. There should then be a short period of time where players can announce their intentions to play, and choose an author/scholar to portray.
On the first turn, each player writes their first entry in the first index. You come up with the name of the entry, and you write 100-200 words or so on the subject. At the end of the article, you sign the name of the scholar you're working on, and make two citations to other entries in the encyclopaedia.
These entries will be phantoms - their names exist, but their content will get filled in only on the appropriate turn. Generally speaking, no category may have more entries than the number of players - and all citations made on the first turn must be in later categories.
On the second and subsequent turns, continue to write entries. Now, however, you need to make 3 citations - one must be a reference to an already-written entry, and two more must be to unwritten entries (either new phantoms, or existing phantoms cited in previous entries). Additional backwards citations are allowed, but you may have no more than two phantom citations.
On your last turn, you need cite 0 phantom entries, and on the second to last turn, you need only cite one.
It is an academic sin to cite yourself, so your scholar may never cite another entry he has written, and may never write a phantom entry he has cited. As the number of entries per turn tend to be limited, phantom entries should be taken/claimed first where possible, and free entries written only after. Scholars are also encouraged to refrain from citing phantoms they have previously cited. This is not, however, a strict rule.
Despite the fact that your peers are self-important, narrow-minded dunderheads, they are honest scholars. No matter how strained their interpretations are, their FACTS are as accurate as historical research can make them. So if you cite an entry, you have to treat its factual content as true! (Although you can argue against the interpretation and may introduce new facts to shade the interpretation).
A player can call dibs on any one phantom entry in either the current index, or the next in line. Whoever calls dibs first, has it. One cannot call 'dibs' on an empty space, and cannot call dibs more than one index in advance.
An author generally belongs to a given player for the entire duration of a Lexicon, and is encouraged to speak with a distinctive voice. Players should not change authors on a whim - there are numerous other techniques to vary writing style and presentation without sacrificing character continuity. Of course, the host of the Lexicon Game is the final judge.