If it's an L seat (or an A seat), it's a "true" window seat. It would otherwise be C or J.
Most IB A340s have the seatmap that you link to, there are 1-2 kicking around that still don't have PY and therefore the entire J cabin is the "other way". You probably have one of these to MEX - I'm guessing there are 12 rows of Business rather than 9?