Ah, I was always looking at Uatu's beautiful art and totally oversaw that section...
Okay, open locks is ranging from 25% to 99% for a thief if I read it right (I assume the 1st edition rules have not changed that much...). AH! Perhaps this means that if I use the GET_OPENLOCKS (or whatever) script, I might have to use values between 0 and 1, e.g. 0.25...