Also, there are plans to use a database for things like these and other stuff, meaning that the data could be queried on demand w/o uselessly filling up memory... but that's not yet on the road map smile.

Note that all the "missing" data from -listxml is basically already there, it's just usually not fully processed. It is, however, already "queried on demand" and displayed in a tree below each game/machine item (in the "full-detail" view only). This process is currently very expensive because the data is searched for in the "raw" -listxml output, and given the many new systems added to MAME within the last year or so, it's no longer "the best approach" to be honest. Anyway, that's the main reason why I can't provide this data as system-notes macros right now.

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]