Lee,
You have x in your function but haven't declared it. I assume its a typo and you mean s, your pointer.
If you are seeing "local variables" (data) used instead of xdata it may be because you did not declare your pointer as xdata.
Just for fun try:
long value(mystring xdata *s)
I always declare my pointers with what type of data (or code) they will point to.
Allen