flag on mensural custos

[Laura Conrad]

I was explaining to someone what a custos was and what it looked like,
and I realized that I have no idea why the flag on the mensural custos I
use goes up sometimes and down other times.  

Reading the documentation
<http://lilypond.org/doc/v2.12/Documentation/user/lilypond-internals-big-page#custos_002dinterface>,
it looks like it's determined by the position on the staff.

Now that I look at them, all the facsimiles I'm using at the moment
(Petrucci, Phalese, and Holborne) only have the upward flag, so what's
the authority for using the downward flag at all?  Has anyone figured
out the code for setting neutral-position so that there aren't any?
(Yes, I could get it on the third or fourth try, but if someone's
already got a snippet...)

For those of you who haven't flipped immediately to the documentation,
it says:

 neutral-position (number)

    Position (in half staff spaces) where to flip the direction of
    custos stem. 

I'd have to set up a test case with custodes on each line and space and
then guess what the default number and direction for this number was and
determine by trial and error what the number I wanted was.  If the
internals documentation would document the defaults for all numbers, it
would save people like me who only try to tweak such things once or
twice a year a lot of time.

And I should report this as a bug, but it looks like lilypond-book
2.12.3 is clipping the flag (which extends past the staff lines).  This
is a regression since 2.10.

-- 
Laura   (mailto:address@hidden)
(617) 661-8097  233 Broadway, Cambridge, MA 02139   
http://www.laymusic.org/ http://www.serpentpublications.org

Mom got to be quite a rabid fan, though...Everything I did was
sensational as far as she was concerned.  Now my father, as far as
*he* was concerned I never got a hit.  If I got a single, my mother
would scream, "Willie's hit a triple."  And Pop would say, "Ach, the
guy should have caught it."

Willie Kamm, quoted in "The Glory of their Times" by Lawrence S. Ritter