| liquid | Shopify Liquid Template |
| lizd | Live Interior 3D Compressed Document |
| llb | Cadence OrCAD Layout |
| llg | LADSIM Ladder Logic Diagram |
| lmk | Sothink Logo Maker Logo |
| lms | LenMus Score Document |
| lmts | Pulsar LMTools Model |
| ln3 | DVILN03 Output File |
| lnb | PRO Landscape Planner Design Backup |
| lnf | PRO Landscape Planner Design |
| loe | LaTeX List of Theorems |
| logicly | Logicly Circuit Data |
| lot | LaTeX List of Tables |
| lox | Therion 3D Model |
| lp2 | iLEAP Document |
| lpd | Label Designer Plus Document |
| lpt | LogPlot Document |
| lqm | LG QuickMemo Notes |
| ls8 | Lumion v8 Scene |
| lsg3x | LinSig 3 Document |
| ltm | IBM Lotus Forms Document |
| ltx | LaTeX Document |
| luf | Lipikar Uniform Format Document |
| lums | SAP Lumira Document |
| lumx | SAP Lumira Discovery 2.0 Document |
| lvw | Livewire Document |
| lwc | Legacy Charting Chart Document |
| lwl | Lightwright Printed Paperwork Formatting Instructions |
| lwo | Lightwave 3D Object |
| lwob | Lightwave 3D Object |
| lwp | Lotus Word Pro Document |
| lws | Lightwave 3D Scene |
| lwsc | Lightwave 3D Scene |
| lxe | Luxology Modo 3D Scene |
| lxf | LEGO Digital Designer Model |