Re: reduce spacing between chord names and staff?

[Paul Scott]

Mats Bengtsson wrote:

> This is controlled by the |minimumVerticalExtent| property of the two 
> involved
> contexts, namely ChordNames and Staff. However, by default the ChordNames
> don't extend below zero, so you probably have to reduce the upper value
> (= the second value) of the property for Staff. Note that this may 
> affect also
> other spacings in the score.
> See 
> http://lilypond.org/doc/v2.1/Documentation/user/out-www/lilypond-internals/Staff.html#Staff 
>
> and
> http://lilypond.org/doc/v2.1/Documentation/user/out-www/lilypond/Vertical-spacing.html#Vertical%20spacing

That's what I thought. 

Ok. With some experimentation I got it to work but from my experiments I 
discovered that \set creates a new staff.  The following creates the 
staff above the chords:

\version "2.1.25"

\header { title    = "Chord Space Test" }

\score {
   <<
   \set Staff.minimumVerticalExtent = #'(-0 . 1)
   \context ChordNames \chords{ a b c d }
   \context Staff \notes{ a'4 b' c' d' }
   >>
}

Is this what is intended?  Where is this feature of \set described?

Thanks,

Paul