The Darlot script looks correct. Ir would be a mistake to assume the 48 is the year. Some even have the name of a person (polishing/assembly/inspection) and micro engraving/etching of letters/symbol codes on the outer rear surface.
Darlot was a big supplier of unmarked lenses to retailers who often put their name on them. I have a "Marion" vesion where the flat inside of the brass lens hood as a tiny AD stamping.