 Discontinuous measurement. These are measurement procedures in which not all instances of the behavior are captured or recorded. I don't know how you capture a behavior. Kind of like you capture a Pokemon. I don't know how you do that either. But anyway, the point being is simple that it's not every single instance of the response class is captured here. So, you know, your momentary time sampling, your whole interval procedures, stuff like that. So, if I'm out of line in the classroom, or I'm out of seat in the classroom, maybe if the teacher is using a time sample procedure, they're only going to catch me out of seat once in a while, right? But they're not going to catch every instance of it, so it will underestimate behavior. There's other issues with these that I don't really want to get into right now, but it's just a category of measurement types. There's lots of different things that fit in this category.