diff --git a/private/attributes b/private/attributes
index fe50b0d..2d6181d 100644
--- a/private/attributes
+++ b/private/attributes
@@ -15,3 +15,5 @@
 attribute sdk_sandbox_all;
 # The SDK sandbox domains for the current SDK level.
 attribute sdk_sandbox_current;
+# Common to adbd and adbd_tradeinmode.
+attribute adbd_common;