Hara Kiri staff behavior

[Richard Shann]

I'm currently baffled by not finding the documentation for Hara Kiri
staffs. That is a staff that only has whole measure rests for a line is
dropped. I thought this was the default, and I thought I had looked it
up before, but now I can only find obscure (to me) references to
RemoveEmptyStaves and the hara kiri engraver
http://lilypond.org/doc/v2.16/Documentation/notation/context-modification-identifiers#index-RemoveEmptyStaves

which says
The following commands are defined for use as context modifications
within a \layout or \with block.

RemoveEmptyStaves


This leaves me wondering what a "command" is in this context - what do I
write inside 

\layout { }

to get the desired behavior? I dpn't even see anything in LSR for
this ... 

Richard Shann