The stories about AA:, AB: etc. are completely bulls**t. The Windows / DOS based systems accept single digit alphanumerical characters as drive letter or rather drive character: A to Z and 0 to 9, so you can have maximum 36 drives. If you want more, you have to mount the additional partitions as folders to existing partitions.
To show what I mean, check this picture. Please click it to show in full size. White text is original command prompt output, yellow text my comments. I'm using SUBST command in this example, syntax is subst DRIVE-LETTER: FOLDERPATH
, where DRIVE-LETTER
is the letter or number you want to assign to folder FOLDERPATH
As you can see, the system accepts drive letters to Z: and single digit numbers, but not double digit numbers or letters.