diff --git a/update_metadata.proto b/update_metadata.proto
index 1a8fd4b..923ea26 100644
--- a/update_metadata.proto
+++ b/update_metadata.proto
@@ -117,6 +117,9 @@
       REPLACE_BZ = 1;  // Replace destination extents w/ attached bzipped data
       MOVE = 2;  // Move source extents to destination extents
       BSDIFF = 3;  // The data is a bsdiff binary diff
+      // SOURCE_COPY and SOURCE_BSDIFF are only supported on minor version 2.
+      SOURCE_COPY = 4; // Copy from source to target partition
+      SOURCE_BSDIFF = 5; // Like BSDIFF, but read from source partition
     }
     required Type type = 1;
     // The offset into the delta file (after the protobuf)