[mapserver-users] WMS client and layers using different CRS namespace prefix

["SAEZ Laurent - CETE Méditerr./DI/ETER"]

Hi list,

I have a question about WMS Client behavior.
I have already post this question in the OGC forum... but nobody answered !
I hope that someone of this MapServer Community has an opinion about it.

In OpenGIS Implementation Specification documents, we can read :
"Maps from multiples servers may be overlaid only if all the selected  
servers have at least one CRS in common".
In France, IGN (Instut Géographique National) has defined his own  
namespace to define french CRS by references. This namespace prefix is  
IGNF. For example, IGNF:LAMB93 references RGF93 - Lambert 93.
My question is very simple ?
Does a WMS client have to determine if CRS using different namespace  
prefixes are equivalent ? Confused
E.g. IGNF:LAMB93 is equivalent to EPSG:2154. In this case, does a WMS  
client have to overlay layers in IGNF:LAMB93 and layers in EPSG:2154 ?

Regards