VerticalExtent on SATB

[Peter B. Steiger]

I finally have a working template that lets me print SATB scores where
the various parts may have extra or different lyrics that break away
from the main melody sometimes.  Now I'm having trouble with vertical
spacing.  I'm using 2.3.11 built from source, downloading 2.3.22 now.

What do the two numbers in the staff.verticalExtent property affect?  It
seems like no matter what I change, the effects are totally
unpredictable.  I added \set Staff.verticalExtent = #'( -5 . 5 ) to the
top staff and the systems are too close together (5 per page) with the
bottom of one system touching the top of another; I change it to -5 . 6
and the systems spread out several inches so there are only two per
page.  I set the staff.minimumVerticalExtent property to (-1 . 1)
because without it the distance is always too large between systems.  I
have tried setting the top and bottom staves to the same values, and
tried setting one to ( -0 . 0 ) and the other to some large number, and
still can't predict which direction everything will move.

There are several measurements I'm trying to control, and from the
examples and documentation and web searches I still have no idea which
properties refer to which distances:
  - distance from soprano lyrics above top staff to top of staff
  - distance from bottom of top staff to alto lyrics
  - distance between alto lyrics below top staff and tenor lyrics above
bottom staff / OR distance between top staff and bottom staff
  - distance from tenor lyrics above bottom staff to top of bottom staff
  - distance from bottom of bottom staff to bass lyrics below bottom
staff
  - distance between systems (from bottom of bottom staff to top of next
top staff)

Other than that, Lilypond is doing a great job of turning illegible
handwritten arrangements into something my friends can read!

-------
Peter B. Steiger
Cheyenne, WY