diff --git a/proto/src/windowmanager.proto b/proto/src/windowmanager.proto
index f26404c6..da4dfa9 100644
--- a/proto/src/windowmanager.proto
+++ b/proto/src/windowmanager.proto
@@ -68,4 +68,8 @@
   LetterboxHorizontalReachability letterbox_position_for_horizontal_reachability = 1;
   // Represents the current vertical position for the letterboxed activity
   LetterboxVerticalReachability letterbox_position_for_vertical_reachability = 2;
+  // Represents the current horizontal position for the letterboxed activity in book mode
+  LetterboxHorizontalReachability letterbox_position_for_book_mode_reachability = 3;
+  // Represents the current vertical position for the letterboxed activity in tabletop mode
+  LetterboxVerticalReachability letterbox_position_for_tabletop_mode_reachability = 4;
 }
\ No newline at end of file