diff --git a/lib/ChangeLog b/lib/ChangeLog
index b54b745..db3c546 100644
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,8 @@
+2006-05-21 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
+
+	* if.h: (struct connected) Document the meaning of the
+	  ZEBRA_IFC_REAL and ZEBRA_IFC_CONFIGURED flags.
+
 2006-05-15 Paul Jakma <paul.jakma@sun.com>
 
 	* log.c: (general) Generalise struct zebra_route_desc into
diff --git a/lib/if.h b/lib/if.h
index 20df7ef..0a4ff14 100644
--- a/lib/if.h
+++ b/lib/if.h
@@ -145,6 +145,12 @@
   u_char conf;
 #define ZEBRA_IFC_REAL         (1 << 0)
 #define ZEBRA_IFC_CONFIGURED   (1 << 1)
+  /*
+     The ZEBRA_IFC_REAL flag should be set if and only if this address
+     exists in the kernel.
+     The ZEBRA_IFC_CONFIGURED flag should be set if and only if this address
+     was configured by the user from inside quagga.
+   */
 
   /* Flags for connected address. */
   u_char flags;