Its a bit american, some threads are non standard like m7, m18
you can get the head sizes by googling 'bolt head sizes'
also worth noting head sizes have a tolerance
It's generic but basically correct, probably based on BS/DIN standards? JIS (lke you'll find on a Subaru) are typically smaller a/f i.e. M8 = 12mm, M10 = 14 etc.
M7x1 is non-preferred but used on all modular alloy wheels
1985 Oettinger 3.2 Caravelle RHD syncro twin slider. SA Microbus bumpers, duplex winch system, ARC 7X15 period alloys