Here is a little guide to the terms generally used when speaking about the lenght of ones hair.
1 Chin Lenght (CL)
2 Shoulder Lenght (SL)
3 Armpit Lenght (APL)
4 Brastrap Lenght (BSL)
5 Mid Back Lenght (MBL)
6 Waist Lenght (WL)
7 Tailbone Lenght (TBL)
8 Classic
9 Thigh Lenght
10 Knee Lenght
11 Calf Lenght
12 Ankle Lenght