I’ve read about availability of a MAME 2015 core, but the latest I see in the core updater is MAME 2014 (using the latest public Retroarch release).
Where do I look to find the latest MAME core, and once found, how do I know which MAME subrelease it is (for ROM set compatibility)? (This may be complicated by the merger of MAME and MESS in May 
Rodney
With the online updater for Windows you get:
UME v 0.159 (Jun 30 2015) <- Mame and Mess MAME 2014 v 0.159 (Aug 6 2015) MAME 2015 v 0.159 (Jan 30 2015)
The romset is 0.159 in all cases
Thanks - very concise and useful answer!
I’m using the online updater on Android, and I may be blind, but I don’t see the MAME 2015 core - nor is it clear, to be perfectly honest, what the difference is between the 2014 and 2015 cores if they in fact use the same romset. =) Any clues on that?
Rodney
The MAME 2014 has been frozen since 0.157 or so. The build date is irrelevant. MAME 2015 is just the latest trunk and is not available on android yet (a broken core was available briefly but it’s been removed)