diff --git a/tuf/encoding/metadata_definitions.asn1 b/tuf/encoding/metadata_definitions.asn1
index c8e45060..f62b85f9 100644
--- a/tuf/encoding/metadata_definitions.asn1
+++ b/tuf/encoding/metadata_definitions.asn1
@@ -164,6 +164,9 @@ TUFMetadataDefinitions DEFINITIONS AUTOMATIC TAGS ::= BEGIN
     num-keyids          Length,
     keyids              SEQUENCE OF KeyID,
     threshold           Threshold
+    -- Pending TAP 5 approval and implementation:
+    -- num-urls            Length OPTIONAL,
+    -- urls                SEQUENCE OF VisibleString OPTIONAL
   }