This file defines the geometry and many logical objects of a track.
Geometry objects are represented by single mesh nodes and won't have any contacts with the cars.
Physical objects are automatically generated when the mesh nodes have a special naming scheme: "<ID><surface name><optional suffix>"
ID must be a number greater than 0. It's unclear if ID has a special meaning as it doesn't has to be unique.
Tracks have a limited list of special objects that are used for the game logic. The best way to create them in Blender is to just place an Empty object.
The engine will use the location and orientation of those.
Every single car needs its own AC_START_X object for a race start. X is the start position, beginning at 0.
The same like AC_START_X but for pit boxes
This one places a virtual pole for a checkpoint. Each checkpoint needs two of them, the left and the right one.
X is the number of the checkpoint where 0 is the start/finish line.
Y is the side of the checkpoint. L for the left and R for the right side. e.g. AC_TIME_0_L and AC_TIME_0_R for the start/finish line
This one marks the start position for a hotlap challenge. It's unknown if there can be more than 1 of these.
There are some things that can problems and should be avoided.
Logical objects that aren't recognized by the engine will cause problems when loading a track. It seems like it just stops loading any further even if there are more things to load.
A mesh node with children will end up in an engine crash.