| lwg | Autodesk LandXplorer Terrain Data |
| lwk | LonghornMax Data |
| lwmw | Likno Web Modal Windows Builder Data |
| lwq | SWAT Lake Water Quality Input Data |
| lwsc | Likno Web Scroller Builder Data |
| lwt | Lightwright Attribute List |
| lwtb | Likno Web Tabs Builder Data |
| lwtp | LimeWire Theme Pack |
| lwtt | Likno Web Tooltips Builder Data |
| lwx | WinTherm RT Radiation Exchange Factors Data |
| lx | LPEX Customization Command Profile |
| lx01 | EnCase Logical Evidence Data |
| lx3 | Lounge Lizard EP3 Exchange Data |
| lxa | Microsoft Speech Lexicon |
| lxd | eDictionary Reader Dictionary Data |
| lxf | Compressed LEN Exchange Format File |
| 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 |
| lyt | Intuit TurboTax Install Log File |
| 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 |