Active LED

[Alarm]

Pretty standard for any sounder.
Now some have a special way of silencing for engineering purposes but this is not one of them.

Engineers Hold Off , eg Texecom, Hint 3 Flash

Any reason for that?
Might as well publish the copyrighted material.

 

[madman41]

3 flash could mean anything :

 

[Alarm]

Age my little trainee, age, not shoe size.