Some text about
original idea behind SOXO, GLUE and more here:
https://www.ibiblio.org/hyperwar/USA...istics1-3.html
Scroll down to page 144.
I believe there's a book by Robert A. Mann about the ins and outs of IARCs, not in my possession.
Use of codes likely changed as war progressed.
Regards,
Leendert