Thanks, Amelie!
> the chords are badly formulated in that all notes are in the same
> octave.
Well, yes, but ...
> That's not a chord, that's a cluster. A few notes should go up an
> octave to make it make sense.
... the customer is always right. :-)
> <c e g d' f'> should, according to nomenclature, be named "C add9
> add11", but is a poorly-formed chord in that it contains a minor 9th
> between the e and the f'. These minor 9ths are usually resolved by
> inversion to a major 7th, yielding <c f g d' e'>, which should be
> named "C sus4 add9 add10".
>
> <c e g d'> is properly called "C add9".
LilyPond does that. It's the border cases I'm worrying about.
Werner