diff --git a/include/android/choreographer.h b/include/android/choreographer.h
index 0389e57..889ecff 100644
--- a/include/android/choreographer.h
+++ b/include/android/choreographer.h
@@ -39,6 +39,12 @@
  */
 typedef struct AChoreographer AChoreographer;
 
+
+/**
+ * The identifier of a frame timeline.
+ */
+typedef int64_t AVsyncId;
+
 struct AChoreographerFrameCallbackData;
 /**
  * Opaque type that provides access to an AChoreographerFrameCallbackData object.
@@ -203,7 +209,7 @@
 /**
  * The vsync ID token used to map Choreographer data.
  */
-int64_t AChoreographerFrameCallbackData_getFrameTimelineVsyncId(
+AVsyncId AChoreographerFrameCallbackData_getFrameTimelineVsyncId(
         const AChoreographerFrameCallbackData* data, size_t index) __INTRODUCED_IN(33);
 
 /**
diff --git a/include/android/surface_control.h b/include/android/surface_control.h
index 3a13104..9a36ecb 100644
--- a/include/android/surface_control.h
+++ b/include/android/surface_control.h
@@ -28,6 +28,7 @@
 
 #include <sys/cdefs.h>
 
+#include <android/choreographer.h>
 #include <android/data_space.h>
 #include <android/hardware_buffer.h>
 #include <android/hdr_metadata.h>
@@ -596,13 +597,23 @@
                                                __INTRODUCED_IN(31);
 
 /**
- * Sets the frame timeline to use.
+ * Sets the frame timeline to use in Surface Flinger.
+ *
+ * A frame timeline should be chosen based on what frame deadline the application
+ * can meet when rendering the frame and the application's desired present time.
+ * By setting a frame timeline, Surface Flinger tries to present the frame at the corresponding
+ * expected present time.
+ *
+ * To receive frame timelines, a callback must be posted to Choreographer using
+ * AChoreographer_postExtendedFrameCallback(). The \a vsnycId can then be extracted from the
+ * callback payload using AChoreographerFrameCallbackData_getFrameTimelineVsyncId().
  *
  * \param vsyncId The vsync ID received from AChoreographer, setting the frame's present target to
- * the corresponding expected present time and deadline from the frame to be rendered.
+ * the corresponding expected present time and deadline from the frame to be rendered. A stale or
+ * invalid value will be ignored.
  */
 void ASurfaceTransaction_setFrameTimeline(ASurfaceTransaction* transaction,
-                                          int64_t vsyncId) __INTRODUCED_IN(33);
+                                          AVsyncId vsyncId) __INTRODUCED_IN(33);
 
 __END_DECLS