"CODOH" stands for "Committee for Open Debate on the Holocaust", the Holocaust denial organization founded by Bradley Smith.
Recently the so-called "Revisionist Forum" has become the official forum of CODOH's website. For several years the forum has been run by UCLA library assistant Jonnie Hargis ("Hannover"), though now several other persons may help to moderate it. The forum is known for its severe censorship of opposing viewpoints - many prominent online anti-deniers have been banned from it basically for effectively debunking deniers' arguments (though false excuses have been given for their banning). But not only anti-deniers are banned. For example "revisionist" Scott Smith, head of alternative forum "RODOH" ("Real Open Debate on the Holocaust") has also been banned.
Bans are not the only tools of censorship at CODOH forum. Many posts just do not make it there (if the poster is in pre-moderation mode), many are deleted, some are edited before appearing. I have experienced this myself, as did many other participants, whether "revisionists" or anti-"revisionists". Not a perfect "1984" emulation, but pretty close.
Recently a Portuguese denier AS Marques, who for some time has been participating in discussions at CODOH forum (and was initially welcome there) complained about Hargis' practices at Bradley Smith's blog. After several replies Smith has simply deleted the whole thread, but you can read most of it here.
So, what do we have here? A "revisionist" complains about Orwellian practices at a "revisionist" forum. Bradley Smith, this self-described libertarian, striving for the "Open Debate on the Holocaust", turns the blind eye on the complaint, dreams up excuses for Hargis' behavior, and then sends the complaint and the ensuing discussion to the Memory Hole.
That's Open Debate for you, folks.
Update: AS Marques says in the comments that his comments were deleted by his request.