[R] levelplot question

[Pedro Mardones]

Dear all;
I have a data set with 3 groups and 2 response variables, say z1 and
z2, and I would like to create a single plot (using the levelplot
function) showing on the first row the leveplots for z1 for each group
and on the second row levelplots for z2 for the same groups. I tried
plot.trellis using the split option and it's OK but what I would like
to achieve is something similar to what you can get in the case that
you'd have 6 groups and only one response, i.e., 3 plots on the first
row, 3 in the second and no space between the first and 2nd rows
(...something like levelplot(z~x+y/group, where group=1,...,6).....).
The first row must have associated the levels corresponding to z1 and
the second row the levels of z2. Does anyone know if this is possible
to do with lattice?
Thanks for any idea
PM