Better to get Width and Height from $21 and $20 of the story file header.

Better to get Width and Height from $21 and $20 of the story file header.

The locations of $22 and $24 in the story file header are for screen
width and screen height.  This is often synonymous with columns and
rows, but is not guaranteed.  It is better to get these numbers from $21
and $20 which are explicitly stated to be for screen columns and screen
rows.