Removes a join between two elements. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 22.0.0.0 (22.1.0.0) 
  Since:  2014 
Syntax
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Parameters
- document
-  Type:  Autodesk.Revit.DB Document  
 The document containing the two elements.
- firstElement
-  Type:  Autodesk.Revit.DB Element  
 The first element to be unjoined.
- secondElement
-  Type:  Autodesk.Revit.DB Element  
 The second element to be unjoined. This element must be joined to the fist element.
Remarks
 This functionality is not available for family documents. 
 Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentException | document is not a project document. -or- The element firstElement was not found in the given document. -or- The element secondElement was not found in the given document. -or- The elements are not joined. -or- The elements cannot be unjoined. | 
| Autodesk.Revit.Exceptions ArgumentNullException | A non-optional argument was null | 
| Autodesk.Revit.Exceptions InvalidOperationException | Please remove or add segments on curtain grids instead of joining or unjoining geometry of the panels. |