trellis: positioning of key

Dear R users,

Using xyplot(), how can I position the key in the *margin* outside the 
plotting area ?

My problem is that the key always overlaps with the x axis labels, no 
matter how I try to specify any of the par() arguments (e.g. oma()).

Evidently that doesn't happen regularly, or someone would have noticed by now. In other words, there's something specific to your example that's causing it. Unless you give us a reproducible example, preferably with all the irrelevant junk edited out, I don't see how we can help.

###
for information, here??s the code I use

par(oma=c(0,0,3,0)) ###this, I think, is what should be changed

?lattice has the following note:

     Lattice plots are highly customizable via user-modifiable
     settings. However, these are completely unrelated to base graphics
     settings; in particular, changing 'par()' settings usually have no
     effect on lattice plots.

-Deepayan