While I think the basic letter system is simple (English alphabet A to Z, 1 through 26, capitalization), there are many operations and conventions based on punctuation, omission, and so on. You cannot find a "textbook" on it, it is his own system.
He uses date stamps and also refers to "Q drops. And often the meanings are only clear when looking at consecutive tweets.
His method is unique and has many different puzzle elements.
I am far from an expert, and there is a lot of "deniable" uncertainty in the meaning of most messages.
Over the last three weeks I have decoded about 30 tweets to my satisfaction, meaning all the visible clues are accounted for, and coherent, with no odd pieces left over.
There are many I cannot figure out. The short ones about sports and irrelevant stuff are the best because they are so obviously NOT about the written subject matter. And I have found a few that I think are gibberish or misleading, meant to confuse his opponents.
"What the hell happened to Global Warming ? Come back fast, we need you !"
