Ok, need a few hints.

[David Kastrup]

Hi, I am currently turning to the problem of typesetting chords for
accordion.  Basically I want to detect the chord/bass input like
ChordNames does, and then do my own translation into bass notes and
chords.  Chord and bass note names also get attached as markup directly
to the resulting notes, and there are some rules for omitting multiple
attachments: successive equal chord names are not repeated, successive
bass _patterns_ are not repeated (loosely the rule might be that as long
as there is no _chord_ change, the last _two_ different bass notes are
not named again: a pattern like C c G c C c G c does just get the first
C c G labelled and then nothing else).

Chord recognizing and engraving is not lossless: c:7 should usually be
transformed to c:7^5.  And a few other things.  In short, it would be
nice to have the chord recognizing machinery of ChordNames run, but
catch the resulting chord name output in list form and do something else
with it, resulting in new voices and annotations.

Ideas?

-- 
David Kastrup