Merge several layers into a single multi-layer GetMap request

[J. Parapar]

Hi all

We have several wms layers with the same wms server in our mapfile
client and MapServer is making one GetMap request for each of the
layers. All the layers have the parameter wms_sld_body set to AUTO. In
some tests with layers without SLD MapServer do merges several layers
into a single multi-layer GetMap request. Does this optimization only
works with non SLD layers?

Thanks in advance,
Jorge