I'm after a specific definition of TM

I doubt there is one, but here's my opinion...

All music is tradition as it all derives and works upon what has gone before it in a process of continuity and development and diversification that could, if one had the means, be traced back to a common ancestral source 50,000 years ago.

Tradition is a couple of guys in Manchester going to see the Sex Pistols at the Free Trade Hall in 1976 and deciding to form a band even though one of them hadn't touched a bass guitar in his life. Within three years they'd changed the face of popular music forever with 'Unknown Pleasures' - an idiomatic masterpiece born of very authentic vernacular experience & inspiration, yet inspirational in itself.   

Music springs eternal, as all human culture will, and must, on a level which is born from as much from the collective subconscious as it is from individual genius. That applies as much to Purcell and Handel as it does to David Bowie and Ian Curtis as it does to Harry Cox and Davie Stewart.

One thing is clear - as long as there are people on Planet Earth, there will be culture, language, art, technology and a myriad evolving musical traditions.

IMHO.