Indicates whether this parameter is driven by a formula or not. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 16.0.0.0 (16.0.0.0) 
  Since:  2016 Subscription Update 
Syntax
Remarks
Note that the value of this property is always the opposite of the IsDrivenByDimension property. It is so because a parameter of which value is evaluated by a formula cannot be driven by a dimension, and vice versa.