Increment Letter in Serial Number?

Hello,

Is there a way that you can increment a letter in a serial number or is it numbers increments only?

It is due to the way an item is produced, a large number of pieces are made, and can go through multiple process steps and we want to use letters to signify the different process steps and make it more easily human readable.

It starts with ABC1234, the parent material

This is then processed up to 20 sub items, using a letter to signify (as one letter takes up less space than two digits).

Now we have sub items ABC1234A to ABC1234T (sometimes less i.e. ABC1234M is the last item)

Each of these are then processed to 20 sub items, also using a letter, to generate more serial numbers i.e. ABC1234AA to ABC1234TT.

Does anyone know if this is possible?