numbers in Betley diagrams

[Trevor Irwin]

In the 100,200 Bentley, in each diagram there is a little box in the lower
right corner with a number xx-xxx. For example in section 35-140-1
Synchronizer, assembling they have the numbers 35-975 in the diagram for
checking the sync rings. It looks like the first two numbers refer to the
repair group (although the 087 forward clutch disassembling/assembling is
in repair group 38, but the number in the diagram there is 36-681). I was
wondering if these numbers are meaningful and if so what their meaning is.
Thanks.

Trevor