Added back section about empty Backlog cancelling a previous Backlog

Commands.md

@@ -50,7 +50,13 @@ If you flashed the device via serial method you can connect to it with a termina
 *The serial interface is set to 115200 bps except for Sonoff Dual and the [Sonoff RF Bridge](Sonoff-RF-Bridge-433) where it is set to 19200 bps.*
 
 ## Using Backlog
-`Backlog` command allows executing up to 30 consecutive commands with a single command line. It is a useful feature to avoid numerous resets when setting up a new device. You can use it to:
+`Backlog` command allows executing up to 30 consecutive commands with a single command line. Each command is separated by a ;. A Backlog command with no following argument clears the existing Backlog queue. Therefore, if a Backlog command was sent with a Delay in it and a subsequent, empty, Backlog command was sent before the Delay expired any commands after the Delay would be cancelled.
+
+So in the case of
+_Backlog Power1 OFF; Delay 3600; Power1 ON_
+if a Backlog was sent after 1 minute the Power1 ON command would be cleared and the Relay would remain off.
+
+It is a useful feature to avoid numerous resets when setting up a new device. You can use it to:
 
 Set up both Wi-Fi AP's
 ```