Halfmoon Systems 
 
Separate Covers
 
On jobs with separate covers, an additional window appears which allows you to enter press, stock, and color information for the cover.  The cover dimensions are calculated by doubling the print width and adding a backbone dimension based on a calculated caliper value for the stock basis and the number of pages. 
  
You may also use the manual stock size selector for covers with the small button next to the Auto Size box.