How to interpret "user 255 key-switch arming" in the D4412/D6412 with no programmed keyswitch zone.

[#1]

When looking at the history log on a D6412 or D4412, the history log displays user 255 key-switch, and the key-switch zone has not been enabled.  The keypad displays as described below:

This will occur when a passcode is not required for arming.  Because there is no user number associated with the arming command, User 255 will be logged.