printed on fabric, then the riggers would sew them in. Sometimes they were not this "neatly" done!
A stencil kit might have been used, a large piece of surplus fabric cut, lay over there stencil made out of cardboard of thick file folder (that's the way we did it in the Marine Corps for 24 yrs
) then spray paint or brush paint over the stencil and there you have it.
Since it was a "field mod" put out by T.O. (Technical Order) The troops in the field could basically comply the best they could.
The tag reads:
CHANGED TO B-15C MODIFICATION IN COMPLIANCE / WITH TECHNICAL ORDER 14P3-10-501 STOCK NUMBER 8415-633-
9613....9613 BEING THE NEW DESIGNATION STOCK NUMBER THE MANUALS CALLED OUT IN THE SUPPLY SYSTEM SO THE NEW JACKET WOULD BE RECOGNIZED.
Just food for thought.
r-Dan