Indicates if this family parameter has an assigned value or not. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
| C# | 
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| Visual Basic | 
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| Visual C++ | 
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Parameters
- familyParameter
-  Type:  Autodesk.Revit.DB FamilyParameter  
 
Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentNullException | Thrown when the input argument-"familyParameter"-is a null reference ( Nothing in Visual Basic) . | 
| Autodesk.Revit.Exceptions ArgumentException | Thrown if the input argument-"familyParameter"-is invalid. |