diff --git a/libsrc/geos/devel/tgi_mode_table.s b/libsrc/geos/devel/tgi_mode_table.s
index 24e2bc88c..4076fbdd8 100644
--- a/libsrc/geos/devel/tgi_mode_table.s
+++ b/libsrc/geos/devel/tgi_mode_table.s
@@ -11,7 +11,8 @@
 
 ;----------------------------------------------------------------------------
 ; Mode table. Contains entries of mode and driver name, the driver name being
-; null terminated. A mode with code zero terminates the list.
+; null terminated. A mode with code zero terminates the list. The first entry
+; defines also the default mode and driver for the system.
 ; BEWARE: The current implementation of tgi_map_mode does not work with tables
 ; larger that 255 bytes!