> what is the meaning of a note that looks like a rhombus in a
> contrabass quartet arrangement?
I don't know how many people are both on the MacPorts and the LilyPond
mailing list (you sent this e-mail to the wrong one :-), so I'm going
to answer that: These notes are 'flageolet tones', also called
'harmonics', i.e., you only slightly touch the string at the notated
position.
> I don't see anything mentioned in the Notation Reference regarding
> this.
There are index entries for both terms.
Werner
