Looking for info about Easy Notation feature

[J. David Blackstone]

  If someone has the time, could you tell me a little bit about the 
coding behind the easy notation feature (the Hal Leonard style
lettered notes)?  I'm sure it'll all make more sense once I get deeper
into the code (just figured out what a grob was a couple of minutes
ago...), but any pointers or overviews someone could provide would
make me real happy.  If I tinker with this feature, will I be working
in C++, Python, or Guile?

  I've been eyeing LilyPond for a few months with a desire to add the
ability to print old-fashioned shaped-note music.  The variable
notehead feature isn't quite what I want: there's a specific shape for
each note of the scale, just like the EasyNotation system.  (I need
them determined automatically rather than having to set each
notehead.)  This may not be useful to anyone else involved in LilyPond
at the moment, but it would be immensely useful to me and some other
people I know.

  There's a design thought that keeps coming up in my mind, too.  It
seems to me that a lot of output features are set in the file that
might work better on the command line.  For example, a song is the
same whether you print it on paper or generate MIDI, but you have to
modify the source file to get the different types of output.  The same
is true for the shaped-note feature I'm talking about, and the easy
notation system, and so on.  I'm just throwing out wishful thinking
here, with no idea how difficult it would be to implement, but I feel
like a separation of music data and presentation data would be a good
idea, either by turning the presentation choices into command-line
options, or maybe even by some sort of stylesheet system.

  But like I said, I'm just throwing ideas that may or may not be
crazy.

  Thanks for the software!

J. David Blackstone