It's simple, a limit is just that. So, if it says the vertical limit is xxxx feet, then that is inclusive.
By way of analogy, speed limit of 80kmh allows you to drive at that speed and you are not over the limit if you drive at such. You are not limited to 79kmh (similar to the contention that the 2500ft restricted area limit finishes at 2499ft). A limit is finite - simple.
Since when did Aviation regulations have to comply with usual english grammar :P
Gen Y, are we?