How do you read the drawdown definition in a prop firm's rulebook before you trade?

Prop-firm drawdown rules are where a lot of confusion starts. Some programmes measure the limit from the starting balance, some from the highest equity point ever reached (a trailing drawdown), and some apply it only to closed trades versus floating equity. The wording in the rulebook usually decides which one applies, and two firms can use the same label for different mechanics. When I read these, I try to pin down three things: whether the reference point moves, whether open-trade equity counts, and whether the limit resets at a fixed time or never resets. I also look for how the firm defines a breach, since some use a close-of-day check and others check in real time. Plenty of people skim this section and assume it works like the last programme they read. Has anyone found a clause in a drawdown definition that surprised them, and how did you make sure you understood it correctly before relying on it?