diff --git a/RNS/Interfaces/SerialInterface.py b/RNS/Interfaces/SerialInterface.py
index e3e48a76..f674266e 100755
--- a/RNS/Interfaces/SerialInterface.py
+++ b/RNS/Interfaces/SerialInterface.py
@@ -7,6 +7,8 @@ import time
 import RNS
 
 class HDLC():
+	# The Serial Interface packetizes data using
+	# simplified HDLC framing, similar to PPP
 	FLAG			  = 0x7E
 	ESC               = 0x7D
 	ESC_MASK          = 0x20