Fender precision bass dating serial numner
This is a practice that actually goes back to Fender's early days.
It therefore appears as though the the S in ICS is only an indication as to whether it is a Factory Special Run or FSR guitar (manufactured by Cor-Tek in Indonesia). The reason they need to do this is because FMIC and the international Fender/Squier distributors have different warranties and totally separate support systems including service centers.
The Standards will be better and any Deluxe or Artist Series instrument can be better still.
That being said it is entirely possible to get an Affinity that is a totally usable instrument.
All the online serial guides, dater software sites etc base all their data exclusively on the FMIC distributed serials.
Therefore it is entirely possible to have a genuine Fender '76 Jazz Bass with a serial that doesn't fit any published format on any website and in cases like that it is because it was shipped from the factory to an international distributor.