Bear Spread and p1/p2 notation confusion

Just looking over the questions and I am wondering why X2 refers to the higher exercise price put option and not the lower one like in the case of bull spreads (with X1 and X2)? Same thing with p2 and p1… any help much appreciated.

Figured it out with the help from these videos. The teacher is a CFA and the videos are money. He covers all the option strategies.

Because you start from Zero to Infinity (which is from the left to right).