moving rest vertically

[Orm Finnendahl]

Hi,

 trying to input my first complete piece with lilypond (Bach's Prelude
#20 from the WTC I), I stumbled across a rather trivial problem: A
32nd rest in a polyphonic 2nd voice collides with a note in the first
voice. Can someone give me a hint how to move that rest down by 1 or 2
staff lines? I couldn't find it in the documentation.

It is sufficient to tell me the "\once \override ..." expression for
the vertical displacement of a rest.

Maybe it would be a good idea to include it in the documetation (if
not already present).

--
Orm