This is a new thread concerning the meanings (if any) behind the field and mint marks of Constantine the Greats SOLI INVICTO COMITI issues.
It is a follow-on from a question I asked jamesicus in the below thread but hopefully others can join in:
https://goccf.com/t/95782The basic background is that I couldn't get my head around some of the Roman mint and field marks so decided to study the coin type I had the most of, Constantine SOLs.
Below is my attempt to visualise the issues chronologically:

Issue years are on the left and mints across the top - the shaded out boxes are Sol issues that have captives in the main image and not in a field or mint mark. The other boxes show all known field and mint variations excluding officinae marks.
Below are observations and theories I have either read or have suggested to try and explain the marks, let me know if any of them sound likely or just plain fantasy!
None of the field marks show any officinae or officinae style control except perhaps the 'A S' and 'B S' issues from Trier in 317 and 318.
I believe the field and mint changes are there first and foremost for management and accountability but also feel they must have some other meaning as they dont follow a set sequence.
Main image captive issues appear in Aquileia and Rome in 312 and in 313 in Ticinum, 313 also sees a captive in a field mark issue from Treveri. (it looks like 'Tr' as I cant track an example down and draw a font, sorry). The above coincides with the Battle of Milvan Bridge (late 312) and later the taking of Rome from Maxentius.
We again see captive issues introduced at Arelatum in 318 (left and right seated types) when Constantine takes Raetia and Pannonia from Licinius in 317. We also see a Laurel wreath issue in Rome around the same time.
We see crescent issues in Arelatum and Londinium in 318 - the crescent symbol has links to fertility and these issues coincide with the birth of Constantius II born in Sirmium, Pannonia (Serbia) 317 (August 7th).
We also see a crescent issue in Rome in 316 coinciding with the birth of Constantine II born in Arelatum (France) 316 (August?).
In 310 we see a '*T *F' issue appear from Londinium, stars have been know to be used to represent the Emperor. We have 2 stars on this coin, it was in 310 that Galerius begins referring to both Constantine and Maxentius as joint Augusti in the West. In 312 and 313 we see a single star on issues from multiple mints, again this is around the battle of Milvan Bridge and Constantines defeat of Maxentius. Is he proclaiming that he is now sole emperor, at least in the West.
Think I'll leave it there for now as checking my dates etc is time consuming, I'll add some other bits and bobs later, I'm not sure I believe any of the above but there seems to have been little study in this area, perhaps little study is the wrong word and I mean little results.
Edited to add a basic coin of the type so people can see exactly which one I mean.

btw - all dates etc are taken from multiple sources but mainly RIC and Helveticas tables which I assume are mainly based on RIC.