Most of us consider 019=9 to be just, "Rhythm Changes".

Rhythm Changes have many different convolutions to them over the years, pays to know the differences between original, old school jazz, bop and modern jazz Rhythm Changes.

BTW, Rhythm Changes are most often played in Bb, with one alternative key being Eb as a sometimes thing. Of course, the consummate musician should practice everything in all 12 keys anyway.


--Mac