Hi, the implementation of CRS Extension seems to be incorrect. There are two wrong definitions in wcs getcapabilities responses:
1. Wrong Namespace URI:
Under point 5.3 (Table 2) of the OGC® - CRS Extension is written, that the correct URI is "http://www.opengis.net/wcs/crs/1.0". Geoserver instead uses "http://www.opengis.net/wcs/service-extension/crs/1.0" in its capabilities xml response. The namespace also should be named "wcs" and not "wcscrs".
2. Wrong XPath for "crsSupported"-element:
The mentioned OGC® - CRS Extension also says, that the "crsSupported"-element has to be a child of crs:CrsMetadata (Requirement 3):
"The response to a successful GetCapabilities request shall contain a crs:CrsMetadata element in the wcs:Extension element of wcs:ServiceMetadata."
The crs:CrsMetadata Element is missing in a geoservers capabilities response. Instead the "crsSupported"-Element is a child of "wcs:Extension"
XPath WCS 2 Standard: /wcs:Capabilities/wcs:ServiceMetadata/wcs:Extension/crs:CrsMetadata/crs:crsSupported
XPath Geoserver: /wcs:Capabilities/wcs:ServiceMetadata/wcs:Extension/wcscrs:crsSupported