The fabrication system name of the service. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 16.0.0.0 (16.0.0.0) 
  Since:  2016 
Syntax
Remarks
 A fabrication system in this context is a set of buttons that can be shared across fabrication services. It has nothing to do with other MEP systems in Revit.