diff --git a/PROTOCOL.md b/PROTOCOL.md
index 116b439..35d8c7e 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -214,8 +214,8 @@ Sequence ID is incremented for each DATA1 packet sent.
 Indices are counted zero inexed from first address byte (2). This means
 the first data is always located at index 0x0e.
 
-The unknown byte was documented as 0x60, but I seem to
-get 0x14 instead. Requires some investigating.
+The unknown byte was documented as 0x60, but I seem to get 0x14 when 
+sending appointments and 0x00 otherwise. Requires some investigating.
 
 Byte 15 indicates how long before appointments, in 5 minute intervals, 
 the alarm will sound.