Spartan-IV numbers and ranks?

Why don’t they tell us either of these? I looked up info on Majestic on halopedian, and it doesn’t even have anything about their rank or number, although they do have a service number, (Thorne’s- 83920-91083-GT). Hardly as cool, though.

Because the IVs don’t get a number like the IIs or IIIs, they keep their last names like the Is.

Nothing is known as of yet, but I’d be surprised if there were.
I made up something when doing the “Who Is Your Spartan?” thing, but that’s about it.

I strongly doubt they follow the same Spartan numbers as did the previous IIs and IIIs.

Service tag on the other hand, everyone would have one. Captain Keys’ tag was long too.

The ten digit sequence followed by the person’s initials is the standard ID system the UNSC uses.

Considering the Spartan-IVs were former Marines/Army troopers, it makes sense that their Service ID would persist even into the Spartan branch.