7700 = EMERGENCY
7600 = RADIO FAILURE
7500 = HI-JACKING
In FS, any code can be used at discretion except those listed above in red : 7700-7600-7500.
When squawking stand-by, controllers can still see the aircraft on their screens but without any tag.
Stand-by is required when on apron, before departure. That way, the pilot does not cause any disturbance in the ground traffic. Stop squawking stand-by when assigned a code (into the departure clearance for instance).
STANDBY mode is accessed via Squawkbox Menu.
Squawk IDENT can also be requested. This highlights the aircraft tag (add 3 slashes) on the scope so that the controller can easily make the difference between two traffics if he/she has a doubt.
IDENT is accessed with the little button in the upper left corner of the Squawkbox window.
A Squawkbox reference...oh man, there's another VATSIM flyer on here? :)
}:-)4