This flag serves two different purposes in two different places.
|Floating point values: Any decimal number (clearer range should be added in Template:Values).
This flag controls the acceleration of units with .
|Signed integers: All whole numbers from -2147483648 to 2147483647; in rare cases, only from -32768 to 32767.
This tag controls the acceleration factor applied to the weapon of this projectile.
If this is 0 the projectile will spawn but stay where it was fired from. An exception to this seems to be when such a projectile is fired and the target is on a different height; the projectile will go up or down accordingly. A unit can only be hit by such projectiles if they go directly into them and if the unit in question was the target. Otherwise no damage at all is inflicted on anyone and the projectile remains at the same height as the target where it was fired from.
It is not clear what results from negative acceleration, but it has been tested that a projectile fired by AircraftTypes with an Acceleration value of -200 will go in wide circles and rarely if ever actually hit the target.Value -2147483648 results in the projectile hitting the target instantly.