I’ve noticed two types of stampings: Numbered and Coded.
Numbered. This seems to be an earlier type. These are “FE” meaning cast iron, “Belgium”, and a single number. The number looks to be centimeters.
Coded. The pieces stamped with the codes seem to be later. Once again, “FE” and “Belgium”, but the numbering looks like some sort of piece code. I am looking at one of my pieces marked: “8 2-D”, for example. BUT as I look through today’s listing on ebay… there’s on marked “80-A 14″. The whole arrangement seems kind of inscrutable, but it does appear that the larger numbers appear on the pot and the small numbers appear on the lid.