COUNTER  Variable  INC|DEC  Amount
   ++/--Variable

This is a command which (INC)reases or (DEC)reases Variable by 
a given Amount.

  Example :

  MyVar =  20
  COUNTER  MyVar  INC  10

  The variable MyVar will now contain "30"

This command is perfect for using in "DoWhile" loops, as a counter.
It also has a simpler and easier form, like the C notation: 

  ++MyVar    - will increase whatever number MyVar
               contains by 1, or
  --MyVar    - which will decrease it by 1.

  MyVar = 10
  ++MyVar       ; now it's 11
  --MyVar       ; now it's 10

MyVar must be a number for this to work.