My understanding is that it is only AGM and the slightly cheaper equivalents that have the coding. Lead acid ones dont.
Yup. I found the same on the EFB batt's fitted to both the Fiat 500 and the Ford KA in my "fleet", each had/have BEM code stickers. Then, EFBs are frequently fitted (at factory) to cars with stop/start. As a cheaper alternative to AGM batts. So BEM codes would be more relevant to them.The EFB battery I had that failed and was replaced under warranty certainly had a BEM sticker.