diff --git a/include/venti.h b/include/venti.h
index 557d242..8c58ab3 100644
--- a/include/venti.h
+++ b/include/venti.h
@@ -93,6 +93,11 @@
 
 /*
  * VtEntry describes a Venti stream
+ *
+ * The _ enums are only used on the wire.
+ * They are not present in the VtEntry structure
+ * and should not be used by client programs.
+ * (The info is in the type field.)
  */
 enum
 {