Hi,
Not much help I'm afraid but anyway,
CLEAR will set all RAM registers to zero. I don't know of a way to selectively clear RAM other than manually doing it, for example with a FOR-NEXT loop like you show.

I'm not sure a SizeOf function would make much sense since arrays can't dynamically resize themself in PBP, you declare them as n bytes (or bits or words or longs) and they stay n bytes long. If you're storing a string for example you can create a subroutine to itterate thru the array and look for your end-of-string character. Could you elaborate a bit on what you need it for, perhaps someone can make a sugestion on how to do it.

/Henrik.