ObjectTemplate.GravityModifier
MDT description
This property has two flavors, one for Objects.con files, the other for Effects.con. For the Objects.con file, the GravityModifier allows you to set gravity per object. 0 means that gravity does not affect the object.
For Effects.con the argument is a CRD, so the amount of the gravity modifier can be randomized.
Source and more details
Additional Description