possible error in lilypond-book documentation: indent and noindent

[Ben Crowell]

I think the following in the lilypond 2.2 documentation for lilypond-book may 
not be
correct:

  indent=size\unit
    sets indentation of the first music system to size, where unit = cm, mm, 
in, or pt. This
    option affects LilyPond, not the text layout. For single-line fragments, 
the default is to
    use no indentation.
  [snip]
  noindent
    sets indentation of the first music system to zero. This option affects 
LilyPond, not the text layout.

This seems to imply that the noindent option would be useless, at least for 
one-line
fragments, since the default is no indentation. Experiments seem to show that 
the default
indentation is nonzero, both for single-line fragments and for multi-line 
fragments.
There is a change when I switch from no options at all to using the noindent 
option.

Then again, I may simply be misinterpreting the manual, or misinterpreting my 
own
experiments.