| tlh | Visual C++ TLH Header |
| tli | Visual C++ TLI Header |
| tmac | Troff Macros File |
| tmc | Windows Trace Message Control File |
| tmf | Windows Trace Message Format File |
| tmf | Trace Message Format File |
| tmh | Windows Trace Message Header File |
| tmk | Turbo Pascal Tour Data |
| tml | Tapestry Markup Language Document |
| tmml | Tcl Manual Markup Language File |
| tmpl | BlueJ Template File |
| tmx | Translation Memory Exchange Document |
| tnm | Synopsys Synplify Time Names Data |
| tok | Borland C++ External Tokens File |
| tom | Tom Source Code |
| tombstone | Android System Tombstone Data |
| toml | TOML Source Code |
| tools | DJGPP Tools Data |
| tox | TouchDesigner Component Data |
| tp1 | SPLat Active Template |
| tph | Turbo Pascal Help |
| tpm | IBM RSA Transformation Parameters Model |
| tpu | Turbo Pascal Unit |
| tpy | TwinCAT PLC Project Variables |
| tr | TCL Trace Output |
| trb | Turbo STK Application |
| trc | Hitachi Ladder Editor Trace File |
| trc | True BASIC Compiled Program |
| trdf | Apache Jena RDF Thrift Data |
| tres | Godot Engine Text Resource Data |
