[Retros] 50 moves rule

[Seth Breidbart]

It seems to me that the underlying issue is the definition of
"position".  Is it a photograph of the pieces on the board?  That plus
information as to whose move it is?  That plus information as to who
might be allowed to castle (and on which side) in the future?
(Consider a position in which White has not castled, his King and
Rooks have not moved, but it can be proven that there is no future
play which involves White castling; how does that count?)

Seth