Use of with() on an mer object

Following John's suggestion I tried
  showMethods(class="mer")
which indeed generated a useful list of functions. This included:

Function: with (package base)
data="mer"

I can't quite think how one might use with() on a mer object. How might 
one be expected to find out?

There were one or two other functions [foo] whose use was not obvious. 
Invariably foo.lme was invisible so ?foo.lme was no help.

Apologies if I've been told all this before. If I haven't used stuff for 
a while it tends to vanish from my memory!

Murray

Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz    majorgensen at ihug.co.nz      Fax 7 838 4155
Phone  +64 7 838 4773 wk    Home +64 7 825 0441   Mobile 021 0200 8350