AA-FF Sistemi
[AA, BA, BB, CB, CC, DC, DD, FD, FF] AA-DD Sistemi
[AA, AB, BA, BB, BC, CB, CC, CD, DC, DD, FF] A-F Sistemi
[A, A-, B+, B, B-, C+, C, C-, D+, D, D-, F] A1-F Sistemi
[A1, A2, A3, B1, B2, B3, C1, C2, C3, D, F]