We will start with a tip from Jim Himes, Rename Layers from a List (Tip #2178). Once you load the LISP code into AutoCAD, type RENLAY to rename a set of layers with new names based on information in a pair of control lists. Before you run this command, you need to modify the contents of the NLL and OLL lists in the source code. OLL contains a list of old layer names, while NLL contains a matching list of new layer names to be used. This program reads through the layers table and when it finds a match with an entry in OLL, it renames the layer to the corresponding entry in NLL. This is a real time saver when changing the layer names on a group of drawings.