Similar to Model Name used with Rooms the Model Name set on occurrences will work as a filter when synchronizing Revit instances with dRofus occurrences. Setting Model Name for occurrences is especially important when synchronizing occurrences from Revit to dRofus. Without setting Model Name the dRofus plug-in will compare Revit instances with all occurrences in dRofus that can lead to unwanted consequences;
You might delete occurrences in dRofus as their key attribute do not exist in the Revit model you are synchronizing from - but might be located in another model. This scenario will only be possible if you actively have set that occurrences should be deleted in the sync options;
When setting Model Name you will ensure that you compare Revit instances in your model with occurrences with matching Model Name or no Model Name set in dRofus. You can still delete occurrences in dRofus, buy now you will only delete occurrences that once was part of you model that has been deleted in Revit.