on the off chance that I'm not the only one on the planet that needs this information, the correct character lookup table appears to be
"0123456789CDFGHJKLMNPQRSTUVWXYZ"
I had to add "S" since I just noticed we have a bunch of iMacs with that code that were looking up wrong since it wasn't in my lookup earlier. ("S" is "late 2016") I assumed they were skipping all the letters that looked like numbers (b/i/o) or other letters (e). I don't know what they thought "a" might be confused with.
If this format holds past "early 2020" and they want to drag it out, they'll probably give up and use a, b, e, i, and 0 at the end also but I have no way to predict that.
I can't believe I googled all over for this information and found nothing more useful than my prior post...
