Building musical chords starting from (a lot of) rules

[Lawrence D'Oliveiro]

In message <mailman.3995.1226685656.3487.python-list at python.org>, Mr.SpOOn
wrote:

> C 9 is a base chord plus a the ninth note, but this implies the
> presence of the seventh too, so it results in: C E G B D

I don't recall such meanings in the chord names I came across. If you wanted
both a seventh and ninth, you had to say so: "C7+9" or "Cmaj7+9".