| 11. | .tr9 | Transis output (Spice) |
| 12. | .tra | Saved game file (Coaster) |
| 13. | .trc | Debug support file (Power CTrace) |
| 14. | .trd | TreeDesigner Document |
| 15. | .tre | Directory tree file (PC-Tools) ◊ ECS/HDS hierarchy tree |
| 16. | .trif | Tiled Raster Interchange Format Bitmap graphics |
| 17. | .trk | Script file (Kermit) ◊ Track (i.e. video sequence) used by many games |
| 18. | .trm | Terminal settings (Windows 3.x) |
| 19. | .trn | Project usage log (MKS Source Integrity) ◊ Translation support file (Quattro - Clarion) |
| 20. | .trs | Executable file (Micrografx) |