THE INPUT FILE: List of invoices for a computer store
WHAT WE WANT: (1) Copy only items for the IBM-PC and the Macintosh.
(2) Move the columns around and put more space between them.
(3) Change the way a negative amount is represented
(i.e. change 345.00- to -345.00).
HOW WE DO IT: (1) We use clustered ACCEPTs to make this selection.
(2) We use SET and PAD for this step.
(3) We use IF to detect the sign, then INSERT it as needed
