[MapProxy] define resolutions and minscale(minresolution), maxscale(maxresoulution)

[Lars Schrader]

Hello,

with the following entry into the services.yaml I find out which 
resoltions I need.

sources:
         - type: debug


I tried the define them with the following syntax:

- osmniedersachsen:
         md:
             title: Omniscale OSM WMS - osm.omniscale.net
         param:
             format: image/png
             srs: ['EPSG:31467']
             res: 
[0.35277759,0.52916638,0.88194397,1.76388794,3.52777587,6.34999657,8.81943968,17.63887936,35.27775873]
             bbox: '3340000.0,5682000.0,3680000.0,5976000.0'
             request_format: image/png
             tile_size: [256, 256]
         sources:
         - type: cache_wms
           req:
             url: http://osm.omniscale.net/proxy/service?
             layers: osm

I only get a black picture with the attribution text insight. If I use 
res: 'sqrt2' it works perfekt.

There's also another question. Can I define minscale(minresolution), 
maxscale(maxresoulution) into the services.yaml?
If yes, how is the syntax for this?

Thank you for providing mapproxy as an open source project. It's great!

Greetings, Lars