| lxk | COREX Lexicon Link-up Data |
| lxl | LPEX Load Macro |
| lxp | MODO Luxology Asset File |
| lxplot | LXFree Plot File |
| lxq | DAZ Studio Frame List Data |
| lxs | LPEX Save Macro |
| lxt | Icarus Verilog interLaced eXtensible Trace |
| lxt2 | Icarus Verilog interLaced eXtensible Trace |
| lxu | LPEX User Profile |
| lxx | LXFree XML Plot |
| ly2 | EAGLE Inner Signal Layer GERBER Data |
| ly3 | EAGLE Inner Signal Layer GERBER Data |
| lyf | LayoutFAST Layout Data |
| lys | DataCAD Layer Control Data |
| lyt | Intuit TurboTax Install Log File |
| lzf | Autodesk 3D Studio MAX Lens Effect Flare Data |
| lzk | LoizziTimeControl Database |
| lzt | HPE Library and Tape Tools Compressed Support Ticket |
| m | Maple Internal Format File |
| m01 | MicroStation Modification User Resource File |
| m02 | MicroStation Modification User Resource File |
| m03 | MicroStation Modification User Resource File |
| m04 | MicroStation Modification User Resource File |
| m05 | MicroStation Modification User Resource File |
| m06 | Microsoft Money 98 Backup Data |
| m06 | MicroStation Modification User Resource File |
| m07 | Microsoft Money 99 Backup Data |
| m07 | MicroStation Modification User Resource File |
| m08 | MicroStation Modification User Resource File |
| m09 | Microsoft Money 2001 Backup Data |
| m09 | MicroStation Modification User Resource File |
| m1 | Juki AMS Embroidery Data |
| m10 | Microsoft Money 2002 Backup Data |
| m10 | MicroStation Modification User Resource File |
| m11 | Microsoft Money 2003 Backup Data |