Western castling doesn’t exist in historical Indian Chess (Chaturanga). Instead, in some versions, there is a cool move whereby each king can once in the game make a knight's move.
I read that it is can’t be used after check. But is that correct? Is it indeed a right which is lost for good after being checked, or is it something which cannot be exercised while the king is in check, but the right will return after the check no longer applies?
I guess I am hoping that it can be exercised even when in check, because it’s so cool to have a chance to escape otherwise certain loss - like James Bond.
How do the two kings interact directly? Must they avoid being a knight move apart. And if one has used its ability can the the other check it allowing bare K to checkmate e.g. K+N?
And how universal in Indian chess is this rule, please?
EDIT: The reason for this is that I think that Chaturanga can be interesting for chess problems, particularly retrograde analysis, but we need to agree a standard "canonical" version of the rules. The get-out-of-jail-free card is a unique mechanism like nothing else in chess, but I can't find a clear definition of how anyone uses it.
EDIT 2: Some relevant links:
The last link given is the most relevant, see John Gollon's account. However, I submit that the text is not clear, and I'm looking for another primary source.