Does the center of the staff need to be zero?

[Kevin Dalley]

In LilyPond, using line-positions, the center is required to be at 0,
otherwise there are problems with the created score.  There are a
couple of possibilities.

One is to make the documentations more clear that staffs must be
centered at 0.

The other possibility is to modify LilyPond to take staffs which are
not centered at 0.

I notice 2 areas which need to be modified.  I have a small patch for
bar-line.cc, which otherwise draws the bar line of the correct size,
but centered around 0 rather than centered around the real center.

Ledger lines need some work as well, though there are problems even if
the staff is centered, particularly if the top and bottom lines are on
even positions.

Should I post my patch for bar lines for staffs which are not centered
at 0?

Here's a comment from the documentation about zero being the center.

The center (i.e. middle line or space) is position 0.
http://lilypond.org/doc/v2.11/Documentation/user/lilypond-internals/staff_002dsymbol_002dinterface

Here's a example of a bad bar position.

\version "2.10"
\new Staff \with {
}
{
  \override Staff.StaffSymbol #'line-positions = #'(1 3 5 7 9)
  \time 4/4
  c''1 | c'' \bar "" | c'' \bar "|."
}