| th | Therion Data |
| th2 | Therion TH2 Map |
| tha | Thunderbird MoreFunctionsForAddressBook Add-on Data |
| the | Microsoft Plus! Theme File |
| theme | Microsoft Windows Desktop Theme |
| themepack | Microsoft Windows 7 Theme Pack |
| thf | LS-DYNA Time History Database |
| thm | Thunderbird MoreFunctionsForAddressBook Mailing Lists Data |
| thp | Intuit TurboTax Tax Line Description |
| ths | Corel WordPerfect Thesaurus Dictionary |
| thu | THUNDER Data |
| thumbdata | Android Thumbnail Data |
| thumbnail | Android Thumbnail Cache Data |
| thumbsdb | PixFiler Thumbnail Database |
| tia | Siemens TIA Portal Data File |
| tic | ArcInfo Coverage TIC |
| tidx | AACS Thumbnail Index File |
| tie | CrossOver v10 CrossTie Installer |
| tig | TI Connect Group File |
| tii | Lucene Term Info Index |
| tika | Apache Tika Data |
| tin | WMS Triangulated Irregular Networks Data |
| tiq | Tektronics RSA306 TIQ Data |
| tis | Lucene Term Infos |
| tit | CXTerm Text Input Table |
| tit | Novapoint Horizontal Alignment Data |
| tjexp | The Journal Exported Data |
| tjf | VAXTPU Backup Data |
| tji | TaskJuggler Include File |
| tjl | HP OpenVMS ACL Editor Journal Data |
| tjp | TaskJuggler Project File |
| tk1 | Wintec WBT-201 TK1 Tracklog |
| tk2 | Wintec WBT-201 TK2 Tracklog |
| tk3 | Wintec WBT-201 TK3 Tracklog |
| tk4 | Wintec WSG-1000 Mark Database |