| layout | Adobe Premiere Workspace Layout |
| layout | Concordance Table Layout Data |
| layout | BookWright Layout Data |
| layoutdesigner | Intuit QuickBooks QuickBooks Layout Designer Data |
| layx | PTV VISSIM Vehicle Network Data |
| laz | LASzip Compressed Lidar Data |
| la_ | TI Databook Data |
| lbd | Nicolet OMNIC Library |
| lbd | Life Balance Data File |
| lbe | Life Balance XML Exchange Data |
| lbg | dBASE IV Label Generator Data |
| lbk | ArchiCAD PlotMaker Layout Book |
| lbo | dBASE IV Compiled Label |
| lbr | EAGLE Library File |
| lbt | Nicolet OMNIC LBT Library |
| lbv | T-Online Ob4hbci Layout Print File |
| lbw | CCP Log Server Log |
| lbxcol | Libronix DLS Resource Collection |
| lbxdtp | Libronix DLS Data Type |
| lbxlls | Logos 3 LLS Data |
| lbxoeb | Libronix DLS Resource |
| lby | Oracle Documaker Library Data |
| lc | L0phtCrack Password Database |
| lcb | Kodak EasyShare Album List |
| lcd | Abbyy FineReader Dictionary File |
| lcf | ArchiCAD Library Container File |
| lcl | LISCAD Lite Database |
| lclw | ClarisWorks Art Library |
| lcm | Lipikar Custom Map |
| lcn | Trymedia License Data |