XRef

XRef stands for eXternal Reference. This is a file (it could be a drawing file or a DGN/DWG/DXF/IFC file), which is added to the drawing file as a reference. The inserted file is still associated with the original file. In other words, the program updates the inserted file to reflect any changes in the original file. An XRef is particularly appropriate for elements you use multiple times (for example, hotel rooms).