1. Before I post the relevant card text, I'll ask the question: Does the term "Block Card" refer to the card that creates the "blocked" status or does it (implicitly) only refer to played blocks?

Chain of Command : E Commit, commit 1 foundation: If you completely block this attack, your opponent discards X cards. X equals the block modifier of the block card .

Does the term "block card" refer only to the source of the block status and not just cards played as blocks (from the hand)? Can cards that generate the "blocked" status, such as Tycho or Vimana, interact with Chain of Command?

2. A while ago, it was ruled that a player could block their own attack with Vimana. Does this old ruling still stand?

Vimana : E Lose X vitality: During the Block Step, this attack is completely blocked and deals no damage. X equals the attack's speed.

With precedence and card text alone serving as proofs, self-blocking is still valid; however, the "rules administration" has changed since the original ruling. I know that James wants this game to make (more) sense (and perhaps eliminate the need for rules arbitration), and self-blocking certainly doesn't make intuitive sense, at least according to my "logic." Nevertheless, if self-blocking even happens in fighting games, most importantly those games within the UFS franchise, then I could argue that the idea of self-blocking does "make sense" in the context of fighting games. Unfortunately I have never played any fighting games, so I am precluded from any further "rationalizations."

Of course, I've devised a few preliminary combos that take advantage of an affirmative response for either (and both) questions.

on the question regarding to CoC it is refering to the card played as a block.

It was ruled, though, that cards that generate blocks will also work with its effect (Mysterious Stance and Seal of Structure were both specifically mentioned).

for CoC: the card that generates the Block (be it by being played from hand or an effect), is the block modifier you use.

vimana: it says "this attack" - so if "this attack" is your attack, then it will block it. (and yes it will trigger CoC if you wanted to do that)

as far as "self blocking" in video games: several games have a Cancel system, where a move can be cut short/interrupted to then go into a new move. so, technically, it's kind of like a self-block. more of a feint, but it's as close as it gets to this situation.