Make the ArcIMS image background transparent

Summary

Background transparency can be set for an ArcIMS Image Service by modifying the *.axl file for that service.

Procedure

1. Open the *.axl file in a text editor.
   
2. Find <PROPERTIES> in the *.axl file.
3. Add BACKGROUND with the color and transcolor attributes. When complete it should look like this:
   
   

   Code:
   <BACKGROUND color="255,255,255" transcolor="255,255,255" />

   
   
   For transparency, the color and transcolor should be the same. Note that all pixels of the specified color become transparent, not just the background.