This circuit board outline is consistent with the dimensions of official RC2014 “Standard” circuit boards.
Where only a single row bus connector is used, this is placed in the position of the lower row of pads.
When working on a 10 mil (0.01 inch) grid, relative to the top left corner, the dimensions in brackets are used for the bus connector.
While the Standard module height is 49.9 mm, other formats have also been suggested by Spencer Owen (developer of the RC2014). These include: Low Profile (25 mm or 38.1mm), Plus (75 mm high) and Jumbo (100 mm high). See here and here for details.
It has also been suggested that an extended width board be used to allow for a full 40-pin long bus connector. This would keep the same general shape, but just extend it by 0.1 inches (2.54 mm).