.RDL File Extension
File TypeMicroStation Redline File
What is an RDL file?
Vector-based drawing format used by Bentley Microstation; saved as a "reference attachment" and is displayed with an active model, such as a .DGN or .DWG file; used for plotting or construction purposes.
RDL files typically have a similar name as the corresponding model they reference and should be saved in the same folder.