Mike Whitaker wrote:
...
>
> As far as I see it, if we *want* abc to require a standard for chord names,
> we have three choices:
>
> 1) don't
> 2) pick one and stick with it, either by democratic vote or the old "I wrote
> the code so I get to choose" argument *grin*
> 3) allow chord 'dialects' so that folks who do it different ways can load up
> the dialect they're used to with a %% directive.
An important point here: this entire discussion has been about
establishing a standard for how abc *playback* programs that tries to
interpret chord symbols. ABC viewers and players that do not add
automatic accompagniment shouldn't be affected at all.
If we want to introduce such a standard at all, we have to find one that is:
a) consequent
b) as simply defined as possible
c) able to express any combination of notes
d) as close as possible to common chord notation
There are definitely some conflicts between those four requirements, but
we can handle that.
I think the main problem is notating chord note alterations. I've been
advocating the use of + and - rather than # and b because that
simplifies the definition considerably.
Example:
The chord C E G Bb D
is notated:
C9
If we want to sharpen the 9th, we can just add a + in front of it:
C+9
That simply won't work with the #/b system. C#9 is a completely
different chord. The usual solution is to add a 7:
C7#9
That's fair enough, of course, but it requires slightly more complex
rules for the poor computer.
In my first posting to this discussion I simply said that the idea was
impossible. I still think it is. That is, it's impossible to define a
set of rules that covers all the major systems for notating chords.
But we don't have to do that. We can just define one particular system
and say "this is what ABC uses".
Then of course we have to allow for local definitons to override the
defaults, such as adding the header field
c: c- = Cm
or
c: c- = [C_EG]
causes the chord "c-" to be interpreted as c minor in that particular tune.
I'm sure there'll be hot debates about the exact syntax for this ;-) but
the general principles shouldn't be too controvertial, should it?
Frank Nordberg
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