The PLT file format is a vector-based plotter file introduced by Autodesk, Inc. and contains information for a certain CAD file. The format is based on the HPGL file format which is used for sending information to plotter printers.
If you have a PLT file, now you can convert it to a dxf file through this application. This way you can use the dxf file for further design, which saves a lot of time.