Chapter 3 of "LilyPond Extending" document

[Peter Gentry]

This chapter headed "LilyPond Scheme Interfaces" would be most useful to the 
tyro since it would help to get information into and
out of music streams.

However it is missing from the 2.18.2 documentation which relates to the 2.16.2 
release.

Inside the 2.18.2 source download there is a file scheme-tutorial.itely which 
refers to the 2.17.11 unstable version. This is
somewhat different from the above but still has no chapter "LilyPond Scheme 
Interfaces"

Is there an intention to provide this chapter or is it a low priority for the 
experts?

Still battling on to fathom a way to recover key signature details for mods to 
enharmonic.ly - currently pondering
key-signature-interface.cc

regards
Peter Gentry