| llb | LabVIEW Library |
| llf | IITM Local Language File |
| llp | VersaPro Compiled Local Logic Block |
| llx | LabVIEW Virtual Instrument Library Backup |
| lmo | Lua Machine Objects |
| ln | UNIX Lint Data |
| lnp | uVision Linker Input File |
| lnt | FlexeLint Configuration |
| lo | Interleaf Compiled Lisp |
| loadtest | Microsoft Visual Studio Load Test Data |
| lobster | Lobster Source Code |
| loc | FactoryTalk View Studio Local Message Component File |
| log4net | Apache log4net Data |
| lols | LOLCODE Source Code |
| lpak | Lobster Program Archive |
| lpb | ProWorx NXT Logic Pointer with Blocking |
| lpf | ProWorx NXT Logic Data File |
| lpg | Sharp Ladder Logic Program File |
| lph | PC-lint Precompiled Header |
| lpi | Lazarus Project Information |
| lpr | Lazarus Program Source |
| lproj | Language Project Folder |
| lps | Lazarus Project Session |
| lpz | Compiled SIMPL Windows Program |
| lref | WPF XAML Cache |
| lrs | Lazarus Resource |
| lsh | Lush Source Code |
| lsk | Liskell Source Code |
| lsl | Altium Designer Linker Script |
| lsml | Visual Studio LightSwitch Model Fragment |
| lsp | Lisp Source Code |
| lss | GCC Assembler Listing File |
| lss | LotusScript Source Code |
| lst | GCC Assembler Listing File |
| lst | IAR System List Output Data |
