Page "Racquetball" Paragraph 18

One set of lines is 18 inches from, and parallel to, the side walls.

Along with the short line, service line, and side wall these lines define the doubles box, where the non-serving doubles partner stands during the serve ; 36 inches from the side wall is another set of lines which, along with the short line and the service line, define an area that the server must not enter if he wishes to hit a drive serve between himself and the nearest side wall.

The receiving line is a parallel dashed line 5 feet behind the short line.