let's say, you are given a crossing restriction of ABC at 12000 feet. prior to reaching ABC, you are handed off, and as you check in with the new controller, you are given another crossing restriction of XYZ at 10,000. are you still expected to cross ABC at 12,000 feet, or can you adjust your descent to the new restriction, i.e., cross ABC lower or higher than 12,000 feet, depending on what that new crossing restriction is?