Triggers...

When you edit waypoints in a chart, you have to pay attention on the following key points about triggering...

Triggering...
A trigger is an area or a volume that releases an event when something enter and/or exit this area or volume.

Waypoints...
The waypoints in EasyATC are cylindric triggers with a variable radius and a constant height auto-generated by EasyATC when the flight plan is built.

Trigger height
The trigger height is the height of the detection cylinder. This value can be changed with the TRIGGER_CHECKPOINT_HEIGHT_TOLERANCE constant. The default value is 10000 ft. That means that if you edit a waypoint at, let say, 6000 ft, EasyATC will consider you are triggering this waypoint if the altitude of your plane is between 1000 and 110000 ft.

Trigger radius
The trigger radius is processed by EasyATC depending on the distance between this waypoint and the two surrounding waypoints. The more a waypoint is close to the one before and/or the one after, the smaller is the radius. This is done to avoid superimposed triggers: if your plane is triggering two waypoints at the same time, EasyATC can deliver inappropriate messages. That said, the processed radius is never smaller than the minimum trigger size constant so the triggers can intersect if you edit two waypoints very close from each other. In this case a message will be displayed when you enable the ATC saying which are the waypoints that are too close.

Track
Between two waypoints/triggers, the ATC expects the plane to fly inside a corridor with a given height and width that fit the altitude and size of the triggers on both side

Plane triggering...
When the plane enters a trigger, the ATC compares the situation of the plane with the last expected track (the line between two waypoints), does some processing and updates or keeps as it is the expected track.

Constraints...
Avoid to close triggers.
The distance between two waypoints should not be lower than twice the minimum trigger radius constant. If not, when in-between the two triggers, the plane can be considered randomly inside the first waypoint or the second one.

Avoid crossings with same altitudes.
To allow crossings, I've added a vertical size on the tracks and waypoints. So if you have one track at, let say, 10,000 ft and another track, exactly below at 5,000 ft everything should work fine, if you keep the vertical trigger and track size constants below 2500 ft (half of the altitude difference).