[Healeys] Official Parts List Question

[rjhco]

The attachment bolts for the crown wheel (ring gear) are listed in the
Official Parts List as:  ATA 7232

According to the fastener reference, the first two numbers are the diameter
in 1/16ths and the second two numbers are the length in 1/8ths.   Clearly,
the system does not work for the above number.  Also, ATA is not listed in
the fastener references.

Can someone please explain the above numbering system?

>From memory, I believe that the bolts are grade 8; 3/8 x 24; one inch in
length.  I don't have access to the bolts at the moment or I would measure
them!

Best regards,
Jim