diff --git a/src/lib/global/nsc.c b/src/lib/global/nsc.c
index 4de0ba87..9aa20246 100644
--- a/src/lib/global/nsc.c
+++ b/src/lib/global/nsc.c
@@ -28,10 +28,15 @@
  *  nsc.c: Empire selection global structures
  * 
  *  Known contributors to this file:
- *     Markus Armbruster, 2004
+ *     Markus Armbruster, 2004-2006
  *  
  */
 
+/*
+ * Convention: uid selector comes first.  Table TYPE has an uid
+ * selector if empfile[TYPE].cadef[0].ca_table == TYPE.
+ */
+
 #include <config.h>
 
 #include <stddef.h>