| kzb | Kanzi Binary |
| lai | GNU Libtool Temporary Data |
| lap | Scheme Source Code |
| layout | Code::Blocks Layout File |
| lba | Liberty BASIC Source Code |
| lbb | LB Booster Program |
| lbj | Learning Based Java Source Code |
| lbk | VersaPro Local Logic Block Backup |
| lbp | ProWorx NXT Logic Pointer Data |
| lbr | Omnis Library |
| lbs | Omnis Application Library |
| lbt | Visual FoxPro Label Memo |
| lbx | Visual FoxPro Label |
| lc | LiveCode Script |
| lc3 | LC-3 Assembly Source Code |
| lc463 | LiveCode Script |
| lc464 | LiveCode Script |
| ldf | ProWorx NXT Logic Data File |
| ldml | Lasso Dynamic Markup Language Document |
| lds | Binutils Linker Script |
| lds | Liquid Studio Source Code |
| ldx | Liquid Studio Compiled Executable |
| less | LESS Style Sheet |
| lfm | Lazarus Form |
| lg32 | GFA-BASIC 32 Library |
| lgf | ProWorx NXT Log Book Note |
| lgo | Logo Source Code |
| lgt | Logtalk Source Code |
| lhs | Literate Haskell Script |
| lib | ESPL Encrypted Programming File |
| lib | Visual C++ Import Library |
| license | Visual Studio Binary License Data |
| licx | Visual Studio License Text |
| lif | HP-UX LIF File |
| lin | µVision Linker Control Data |
