| tjf | VAXTPU Backup Data |
| tji | TaskJuggler Include File |
| tjl | HP OpenVMS ACL Editor Journal Data |
| tjp | TaskJuggler Project File |
| tjvdb | The Journal Volume Database |
| tjxml | The Journal Export Data |
| tk1 | Wintec WBT-201 TK1 Tracklog |
| tk2 | Wintec WBT-201 TK2 Tracklog |
| tk3 | Wintec WBT-201 TK3 Tracklog |
| tk4 | Wintec WSG-1000 Mark Database |
| tka | Genie 2000 Measurements Data |
| tkb | TicketBench Data |
| tkc | MetaTrader 5 Tick Data |
| tkd | Wikit TKD Database |
| tki | Tkined Data |
| tks | NI Traktor Pro MIDI Map |
| tkt | TK Solver Data |
| tkw | TK Solver Data File |
| tkx | TK Solver Package |
| tl5 | Timeliner 5 Data |
| tlb | HP OpenVMS Text Library |
| tlbackup | True Launch Bar Settings Backup |
| tlbbackup | True Launch Bar Settings Backup |
| tlbplugin | True Launch Bar Plugin |
| tlc | TINA Logic Converter Data |
| tld | PTC Creo Thermal Temperature Load Data |
| tld | TINA Library Descriptor |
| tle | STK Two-line Element Sets |
| tlf | Timing Library Format File |
| tlist | Geomview Transformation Matrices Data |
| tll | LG TV Link-Loader File |
| tlm | Spektrum DX8 Telemetry Log |
| tln | HyperLynx LineSim Schematic |
| tlo | SPSS Table Look File |
| tlog | ArduCopter Telemetry Log |