improved a comment
diff --git a/aos/atom_code/ipc_lib/aos_sync.h b/aos/atom_code/ipc_lib/aos_sync.h
index 6d4bf55..ddbe3d0 100644
--- a/aos/atom_code/ipc_lib/aos_sync.h
+++ b/aos/atom_code/ipc_lib/aos_sync.h
@@ -48,6 +48,8 @@
// They are designed for signalling when something happens (possibly to
// multiple listeners). A mutex manipulated with them can only be set or unset.
//
+// Another name for this kind of synchronization mechanism is a "notification".
+//
// They are different from the condition_ functions in that they do NOT work
// correctly as standard condition variables. While it is possible to keep
// track of the "condition" using the value part of the futex_* functions, the