Making sense of tunic size markings?

[Les]

Does anyone know for certain what the size markings on pre-1918 tunics specifically indicate? (The WWII era system is different.) For example, on the left is a single number (i.e., "42"), then to the right are two other sets of numbers, for example, 96 over 86, and then 45 over 64. Does the first single number indicate neck size, and the others size ranges for the chest, and then for whatever the next group is? If that's the case, what's the range of the last group represent?

[Hoss]

Waist length 42 Breast size 96 (body length 86) collar width 45 (sleeve length 64)

Eric

[Les]

Eric, ta!