server side simultaneously plot two layers

[Reimar Bauer]

The "WMS-correct" way of doing this would be add a layer on the server side that returns a map displaying the desired data. Two options: Extend the server so that it can simultaneously plot two layers (that is defined in the WMS standard)

We can work on this after we migrated the owslib to a more recent version

[Reimar Bauer]

For which kind of layers was that feature defined. I need an example.