groups and WMS

[Armin Burger]

Dear all,

I have a question about the behaviour of groups in a WMS. When I define 
2 layers belonging to the same group, I see both layers nested under the 
same group layer in the capabilities file.

But I can only access the group as a WMS layer from a client. When I 
want to access the single layers belonging to that group I get an 
exception. That is in principal ok, but client programs might allow to 
select the single nested layers and the map will not be displayed 
because of the exception. Also the reason for grouping layers is quite 
often to have layers with different accuracy/resolution that should be 
swapped depending on the scale. So this should happen behind the scenes 
without the client noticing it.

So my question is, why are the layers belonging to the same group 
displayed at all in the WMS capabilities if they cannot be used as 
single ones? Would it not make sense to just return the group as a WMS 
layer instead?

Armin