Main sections
DEC
DEC x##, [num#$=1]
DEC x$$, num#$
Decreases the value of tha variable x## or x$$ by the value of 'num#$'. This works with array variables too, obviously.
a = 100
DIM b[5]
b[3] = 200
DEC a, 5
DEC b[3], 5
PRINT a, 100, 100
PRINT b[3], 100, 120
SHOWSCREEN
MOUSEWAIT
Output:
95
200
Note : If num is not given, then the value in the variable is decreased by 1