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out of date.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 modify expression
The expression cannot be modified using the Debug menu's
Modify Value command without causing an error.
Try altering the expression in the program code,
recompiling, and running your program again.