WPC games seem to have a 'type' of rom of the list: (H,A,X,G,F,B,R)

H=home, A=domestic (usa/american) - X=export - not sure what 'G,F,B,R' would refer to. If you go by system 11 roms, G is likely 'German' and F is likely 'French'.

Some already use the 'B' designation (AFM 1.13B, and MB 1.06B), and AFAIK those aren't 'hacked' versions (it's literally a single byte difference in the rom, and the B was already present there, not something someone added).

Interestingly there was no P designation at least in the couple I looked at, for 'Prototype'. (Unless that's what the R would be for? To make it more dissimilar from F or B?)

Thoughts on GFBR meaning? Maybe an old Uncle Willy covered some of this and I've forgotten over the years.

Just curiosity's sake, but it's nice to know the minutiae.

So here's the source for system 11 type roms, would have no reason to think they didn't carry some of that over to WPC era.

http://www.planetarypinball.com/mm5/Williams/tech/sys11roms.html

System 11 games have the software revision identified with either an "L" or "P" followed by a revision number, such as L-1 or P-1. The "L" signifies a production ("Level") release, while the "P" signifies a Prototype version of software. Sometimes contained within the revision label is a version identifier, such as LX-1 or LA-1. The possible version identifiers are the described below.

Not all versions exist for all games.

No suffix: Unrestricted. This version supports all text languages, can be priced for any country, and contains the custom pricing editor.

A: USA and Canada (domestic). This version does not contain the custom pricing editor, and does USA and Canada pricing modes only.

X: Export. This version contains the custom pricing editor, as well as the built-in pricing presets for all countries.

R: Regular. This version does all pricing modes, as well as the custom pricing editor, but does not contain French text.

F: France. This version is the same as the R version, with the addition of French text.

B: Belgium/Switzerland. This version contains French text, does not have the custom pricing editor, and does Belgium, Switzerland, and Canada pricing modes only.

G: Germany. This version contains support for special German functionality, such as German speech.

Yes, the revisions I posted are hard-coded in the OS (at least in the game I looked at). Wouldn't stop someone from changing an X to a G for ghosting, which isn't technically correct.

So far it's looking as though the system11 from planetary is carrying through. They probably didn't release French or German because that's embedded in the roms (language), but the designation might exist for the sound roms.