AutoCAD 2013 :: Constructing A Grid (centers) With Letters And Numbers

Constructing a grid (centers) with letters and numbers,I follow to set a grid for a plan (All what I need here is a lisp file that provides serial numbers and letters for the grid):

-Grid (centers) are provided to the existing columns
-Circles are plot at the end of these centers to accommodate labels
-Numbers & letters labels are provided
 -Numbers and letters are edited to put them in serial order. Here is the issue, as serial number and letter is done manually, then this is a source for errors!
 
The attached lisp file  does do this sort of work but doesn’t allow choosing the direction of numbering lettering! In the same plan, if I need to have the numbers to start from right (instead of starting from left) then this is impossible using that lisp. This is the only part of the code that needs to be enhanced. Also, the “auto number” command does the same thing but work with numbers bit not for letters.