qbasic.hlp (Topic list)
Important Notice
The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.
Cannot start with 'FN'
You used "FN" as the first two letters of a SUB or a
FUNCTION procedure or variable name.
 
"FN" can only be used as the first two letters when calling
a DEF FN function.