diff --git a/README.md b/README.md
index 5811367..50b4124 100644
--- a/README.md
+++ b/README.md
@@ -124,4 +124,6 @@ In order to unify the way we write code and talk about concept the following
 terminology definitions should be followed:
 
 - frame (data from a single module)
-- image (data of the assembled image)
\ No newline at end of file
+- image (data of the assembled image)
+- start_pulse_id and stop_pulse_id (not end_pulse_id) is used to determine the 
+inclusive range (both start and stop pulse_id are included) of pulses.
\ No newline at end of file