Is there a consensus on the meaning of the Δ seen on Ptolemy tets? I've seen it referred to as "the signature of the master engraver."
There are several small letters like DELTA (also KAPPA, ETA) that appear on some tetradrachms (maybe some other
types). The DELTA is seen on many
types over a long time period so it may be a stretch to link it to a particular person unless that person was an extraordinarily prolific die cutter. OTOH, it might be the 'signature' of a person on some dies but not others. Some dies that bear such marks are better artistically than others. Then again, maybe the letters denote workshops.
The small letters tucked into small spaces in the design don't seem to play a big role in cataloging
types like ordinary control letters,
monograms, and design elements do. Maybe they
help give some coins a nifty
legend. Imho the artistic
quality of the die matters much more than whether or not one of the small 'hidden' letters is present. If only those coin makers
had left us a better written record of what they were doing...
PtolemAE