diff --git a/src/osgPlugins/rgb/ReaderWriterRGB.cpp b/src/osgPlugins/rgb/ReaderWriterRGB.cpp
index fb929e93b..95c8d6554 100644
--- a/src/osgPlugins/rgb/ReaderWriterRGB.cpp
+++ b/src/osgPlugins/rgb/ReaderWriterRGB.cpp
@@ -1,3 +1,8 @@
+// Released under the OSGPL license, as part of the OpenSceneGraph distribution.
+//
+// ReaderWriter for sgi's .rgb format.
+// specification can be found at http://local.wasp.uwa.edu.au/~pbourke/dataformats/sgirgb/sgiversion.html
+
 #include <osg/Image>
 #include <osg/Notify>