Question please on conference type...

Hey guys,
When inside a db file, where you can edit conference names, there is a column thats labeled "conference type" like 10a, 13b, 14c for example. I know the number represents
how many teams are in the division but what does the letter after the numbers mean??? I couldnt find an answer on it anywhere. Same with the "tournament type", I have no idea what
the letters after the numbers represent... can anybody tell me what they mean please? Thanks so much in advance!!
When inside a db file, where you can edit conference names, there is a column thats labeled "conference type" like 10a, 13b, 14c for example. I know the number represents
how many teams are in the division but what does the letter after the numbers mean??? I couldnt find an answer on it anywhere. Same with the "tournament type", I have no idea what
the letters after the numbers represent... can anybody tell me what they mean please? Thanks so much in advance!!