Manually editing the EPSG database

Warning

These instructions are very advanced, and are here mainly for the curious who want to know details about the EPSG database subsystem.

To define a custom projection, edit the EPSG.sql file, which is used to create the cached EPSG database.

Navigate to the WEB-INF/lib directory
Uncompress the gt2-epsg-h.jar file. On Linux, the command is:
```
jar xvf gt2-epsg-h.jar
```
Open org/geotools/referencing/factory/epsg/EPSG.sql with a text editor. To add a custom projection, these entries are essential:
1. An entry in the EPSG_COORDINATEREFERENCESYSTEM table:
```
(41111,'WGC 84 / WRF Lambert',1324,'projected',4400,NULL,4326,20000,NULL,NULL,'US Nat. scale mapping.','Entered by Alex Petkov','Missoula Firelab WRF','WRF','2000-10-19','',1,0),
```
  where:
  - 1324 is the EPSG_AREA code that describes the area covered by my projection
  - 4400 is the EPSG_COORDINATESYSTEM code for my projection
  - 20000 is the EPSG_COORDOPERATIONPARAMVALUE key for the array that contains my projection parameters
2. An entry in the EPSG_COORDOPERATIONPARAMVALUE table:
```
(20000,9802,8821,40,'',9102),    //latitude of origin
(20000,9802,8822,-97.0,'',9102), //central meridian
(20000,9802,8823,33,'',9110),    //st parallel 1
(20000,9802,8824,45,'',9110),    //st parallel 2
(20000,9802,8826,0.0,'',9001),   //false easting
(20000,9802,8827,0.0,'',9001)    //false northing
```
  where:
  - 9802 is the EPSG_COORDOPERATIONMETHOD key for the Lambert Conic Conformal (2SP) formula
3. An entry in the EPSG_COORDOPERATION table:
  
  (20000,'WRF Lambert','conversion',NULL,NULL,'',NULL,1324,'Used for weather forecasting.',0.0,9802,NULL,NULL,'Used with the WRF-Chem model for weather forecasting','Firelab in Missoula, MT','EPSG','2005-11-23','2005.01',1,0)
  
  where:
  - 1324 is the EPSG_AREA code that describes the area covered by my projection
  - 9802 is the EPSG_COORDOPERATIONMETHOD key for the Lambert Conic Conformal (2SP) formula

Note

Observe the commas. If you enter a line that is at the end of an INSERT statement, the comma is omitted (make sure the row before that has a comma at the end). Otherwise, add a comma at the end of your entry.

After all edits, save the file and exit.
Compress the gt2-epsg-h.jar file. On Linux, the command is:
```
jar -Mcvf gt2-epsg-h.jar META-INF org
```
Remove the cached copy of the EPSG database, so that can be recreated. On Linux, the command is:
```
rm -rf /tmp/Geotools/Databases/HSQL
```
Restart GeoServer.

The new projection will be successfully parsed. Verify that the CRS has been properly parsed by navigating to the SRS List page in the Web administration interface.