| lcf | ArchiCAD Library Container File |
| lcl | LISCAD Lite Database |
| lclw | ClarisWorks Art Library |
| lcm | Lipikar Custom Map |
| lcn | Corel WordPerfect Dictionary Data |
| lcn | Trymedia License Data |
| lcp | FARSITE Landscape Data |
| lcpl | Readium License Document |
| lcs | Alstom MMS LCS Compiler Report |
| lcs | L0phtCrack Password Database |
| lcs | Light-O-Rama Compressed Sequence File |
| lcv | Radio Mobile Land Cover Data |
| lcx | LC Model |
| ld | Corel Paradox Language Driver |
| ld | MoTeC Telemetry Log |
| ld1 | dBASE IV Overlay File |
| ld2 | Lingoes Compiled Dictionary |
| ld2 | LogDator Measurement Data |
| ld4 | AccPac Plus Menu Data |
| ld9 | PADS Layout Library CAE Decal Data |
| ldabak | Legistant Encrypted Backup |
| ldata | JSim Line Data Format |
| ldb | Lingoes Dictionary Backup |
| ldb | Microsoft Access Database Lock |
| ldb | Sybase PowerDesigner Logical Data Model Backup |
| ldb | TrueVector Log Database |
| ldc | Steuer 2001 Data File |
| ldd | Laser Dispatch Data File |
| ldd | LEGO Digital Designer Data |
| lde | Veeam Explorer Exported Data |
