I was trying to connect a WMS client to the GeoServer installation and it crashed saying that WGS84(DD) was not a valid number. On checking I see that the default installation of GeoServer includes the SRS EPSG:WGS84(DD) as the first item. Clearly that applicaion should not have crashed but on checking with the OGC standards 1.1.1 (http://portal.opengeospatial.org/files/?artifact_id=1081&version=1&format=pdf - http://portal.opengeospatial.org/files/?artifact_id=1081&version=1&format=pdf) I found the following.
18.104.22.168 EPSG Namespace for SRS
The EPSG namespace makes use of the European Petroleum Survey Group tables
, which define numeric identifiers (the EPSG "CRS code," corresponding to the
field "COORD_REF_SYS_CODE" in the EPSG database) for many common projections
and which associate projection or coordinate metadata (such as measurement units or
central meridian) for each identifier. An SRS name in the EPSG namespace includes only
the prefix and the identifier, not any additional parameters. This format is used both as
the value of the SRS parameter in a service request and as the value of an <SRS> element
in the Capabilities XML.
This clearly states that the value after EPSG: should be a numeric identifier. It is my opinion, therefore, that the default installation should not include this value.