A funny one this in 960

rkrbnnbq/ppppp1pp/8/5p2/5P2/8/PPPPP1PP/RKRBNNBQ w CAca f6 0 2

Here is a PGN of a games in progress. It is NOT my game, but the initial Back Rank Positions are the same for both sides as thay were at the start of the game.

It seems ro me that both players may only castle to one side by virtue of the Two Rooks flanking the King with one Rook in a corner.

I am wondering if the initial position is "legal", or perhaps valid is another way of putting it.

Odd one this. Any answer from a 960 expert please?  

I am not good at diagrams, but here is my try. But after insertion it seems OK.

It's perfectly legal. White can castle 'queen' side once the Rc1 and Bd1 have moved away. Or can castle 'king' side if Bd1, Ne1, Nf1 and Bg1 have moved off. This is position 957 in the 960 start positions, see table here for example: http://www.mark-weeks.com/cfaa/chess960/c960strt.htm.