I'm planning to add a software list for the Fujitsu FM-8, and I'm having a bit of a dilemma right now.

Currently, all the FM-8 software is part of fm7_cass.xml. This is because the FM-7 uses very similar hardware and is backwards compatible with the FM-8 (yes, the FM-7 was released later), but ideally I'd want to configure the list in a way that it only shows FM-8 software when you run that machine.

As far as I know there are two ways to do that: either split the FM-8 compatible software to its own list and add it to both the FM-7 and FM-8 machines, or keep everything in one list and use compatibility tags (<sharedfeat name="compatibility" value="...") to filter what's shown. So that's my question: are there any situations where one of those options is recommended over the other? Which one would fit this case better?

Generally in that situation I'd say put the older machine's software in its own list and add it to both - that's what we did for the 8-bit Apple II stuff.

In this case I’d recommend putting the FM-8 software in its own list and adding it as a “compatible” list to the FM-7.

Well, thankfully that's what I was working on before I started having doubts, so now it's only a matter of cleaning up the list a bit and submitting the PR. Thanks!

E.g. the PAL and NTSC versions of VCS2600 carts should also have some kind of sublists. Although they can be inserted into the wrong console, the result are wrong colours and in real life rolling picture (often in B/W when having NTSC games on PAL - which did not prent clone console companies from including wrong versions).

That's what compatibility tags are for.