When a contrail is selected in the Levels Window, its properties may be edited using the Properties floating window (Command-0), as described below:
Contrail Name Field
Determines the name of the selected contrail
Contrail Type Pop-Up Menu
Determines the selected contrail's type. The Edit button may be used to edit the game project's contrail types, as described in the Contrail Creation section.
Location X and Y Fields
Determines the initial location of the selected contrail
Current Horizontal Speed Field
Determines the initial horizontal speed of the selected contrail
Current Downward Speed Field
Determines the initial downward speed of the selected contrail
More information on contrails is available in the Elements of a Game section.