The range of acceptable Control Identity numbers for GUI programs?

[f_la_f]

Is there a range of legal Control Identity numbers applicable to BCX GUI programs?  I recall reading somewhere in the dim, dark past, that these were limited between 100 though 199 inclusive.  I had problems a few years ago with several controls above 140, being that these controls were occasionally influenced while operating some other GUI programs (not mine).  Perhaps this problem was due to a bug or two in my program.  Nevertheless, as a precaution, I have since avoided such ID numbers, but I'm curious as to whether there is a preferred range of GUI control numbers.  For example: I have not seen a BCX program example with a control ID less than 100.

Frank