Files with unit translations (for region-specific units of measure) are loaded AUTOMATICALLY by the system following the pattern: xx-YY.xpux, where xx stands for the language code and YY stands for the country code. For instance, en-US.xpux is the name of an English file for the United States region, whereas de-DE.xpux will apply German translations. The files can be found in the xpdrainage installation directory, and the application will load all of the *.xpux files found in the installation directory at runtime. Any customised unit files will have to be placed here by the user prior to opening xpdrainage.

To produce a customised unit file:

1. In xpdrainage, open the File->Preferences menu option
2. Click the ‘Edit’ button to open the ‘Units’ dialog
   
   
   
3. Modify the units for specific measures 

4. After the units have been set, save the file with the name pattern described in the previous paragraph

To edit the .xpux file:

1. Load Notepad.exe or any text editor, and navigate to the xpdrainage installation directory (usually C:\Program Files (x86)\XP Solutions\xpdrainage)
2. Open the newly-created .xpux file, and enter the appropriate region after the XPDUnits tag
    
    
3. Save the file, and run xpdrainage
4. The name of the region will then appear in the Region combo box in the ‘Units’ form as a selection choice.