Cohort commander?

[D B Campbell]

However, the cohort is also used as a unit manning a castellum. In this case, the cohort would have been supervised by the castellum commander, which we believe to be a legate or prefect. The six centurion would be in charge of their assigned body of men and would make up the cohort staff, along with an administrator.

You are describing an auxiliary cohort, Robert. Your "castellum commander" (actually the cohort commander, usually) would be an equestrian officer: a prefect or tribune, not a legate. (Not sure what you were envisaging with your "administrator".)

I'm guessing the text reads: "(something was built) by a detachment of legions I Italica, V Macedonica, XI Claudia and six cohorts under (the command of) Malicus, centurion of legion XI Claudia." Does that look right? Still doesn't explain what the six cohorts were though... :unsure:

Ah, the perils of trying to interpret an inscription without its context!

AE 1995, 1348 was found at Parutino (Ukraine), ancient Olbia, where a second/third century fort was apparently garrisoned by troops seconded from Moesia Inferior, home of the I Italica, V Macedonica and XI Claudia, besides assorted auxiliary units. The site has (apparently) produced tile-stamps of I Italica, V Macedonica, and cohors VI Asturum.

According to AE, the inscription -- which I have not seen -- reads:
--]R VEXIL
--]I ITAL V MAC
--]T C VI MA
--]LICO > LEG XI CL

You can see that the centurion is unlikely to have been called Malicus ... unless he spelled it Maaaaaaaalicus! Without seeing the stone, it's difficult to know how much is missing from the left, but Sarnowski (whose publication is reported in AE) seems to think that there was space to name XI Claudia in the vexillation breakdown. (The fact that the commander came from XI Claudia needn't imply that legion's participation.) And it seems odd (to me) to abbreviate cohors VI Asturum as C VI. But these things are sent to try us.

Incidentally, you are correct that the inscription seems to be a building record, not a tombstone.