diff --git a/Demo/rpc/T.py b/Demo/rpc/T.py
index 24d5e8ae3e4..475372bfff6 100644
--- a/Demo/rpc/T.py
+++ b/Demo/rpc/T.py
@@ -1,3 +1,6 @@
+# Simple interface to report execution times of program fragments.
+# Call TSTART() to reset the timer, TSTOP(...) to report times.
+
 import sys, os, time
 
 def TSTART():