ArcIMS supports several thousand projected and geographic coordinate system identifiers. The WMS specification refers to these as SRS identifiers. It is not practical to include all these identifiers in a Capabilities file. By default, a Capabilities file contains a minimum number of identifiers: 4326 (WGS84), 4269 (NAD83), and 4267 (NAD27). You can add additional identifiers to match the expected needs of clients requesting data.
The format for each identifier is <SRS>id number</SRS>:
<SRS>4326</SRS>.
A complete list of SRS identifiers is available in the ArcXML Programmer's Reference Guide: