SISC means 4th
officina of
Siscia mint.
It is usually hard to tell exactly what any
field marks mean, other than signifying specific issues, likely for administrative tracking, accounting and
security purposes.
However, the marks for the
SECVRITAS REIPVBLICAE and
GLORIA ROMANORVM types at
Siscia are very interesting. When you remove a few marks that are likely errors or misreadings (there are several marks that have never been seen on another coin since the book was published in 1933 are so are very likely mistakes) then what remains is interesting as the letters, especially those on the right
side for SR and left
side for GR, appear to be annual marks. They generally appear in groups of three. So A k / F, k A / F and D k / F. Three issues with k/F combined with a different letter. This goes on for all years between 368 and 375.
This led Lanyi to the, what I believe is correct, conclusion that these related to the quadrimestrial (every four months)
military pay cycle that we know existed.
So this is likely one of the few
types and mints that we have a fairly likely explanation of the "meaning" of the
field marks. We don't know why they used any specific letter or symbol but at least we can see a pattern.
SC