Coordinate Reference System (CRS) definitions will be provided by the EPSG database. However we need an easy for allowing users to provide their own CRS, because updating the EPSG database is uneasy. One of the easiest way is to provide a list of CRS as plain key - value pair, where the key is the code and the value is the CRS in WKT (Well Known Text) format. Such pairs can be provided in two ways:
- As *.properties files
- In the PostGIS spatial_refsys table.
This issue is only about properties files.
The above CRS codes are valid only in a namespace. The easiest way to specify the namespace would be to use the name of the properties file. So a “custom.properties” file might define the CRS in the CUSTOM namespace.
One open question is where (in which directory) to put those files.