Remarks

value 0 for default behaviour. And -1 for special behaviour
When a string is stored with a DATA statement, a null is added to indicate the string end. In some situations you might not want this. When you write a custom routine to work with a long string for example. With $NONULL = -1 , the additional null byte is not added. To switch back to normal mode use a value of 0.

See also

Example
$NONULL = -1
lbl:
DATA "test", "this"
lbl2:
$NONULL = 0 'normal mode
DATA "test", "this"