The coordinate systems dialog is used to select a coordinate system. Internally, MapGuide Open Source uses Well Known Text representations of coordinate systems. The server does not advertise which coordinate systems it supports so Web Studio includes a configuration file that you can modify to include your commonly used coordinate systems. The coordinate systems dialog lists a descriptive name and EPSG code for each entry in the projections.xml file. Select a projection from the list and click ok to choose a projection.
To modify the list of available projections, edit the projections.xml file. For your convenience, all-projections.xml contains projection definitions for all EPSG codes, including commonly used codes that are beyond the EPSG range. If you know the EPSG code, simply search for it in all-projections.xml and copy the entire projection tag into projections.xml.