| ytf | YTGen Population Data |
| ytm | YTGen Method Data |
| ytp | madVR Test Pattern |
| ytr | IRIS OCR Data |
| yum | YUM Data |
| yumtx | YUM Transaction Data |
| yves | YVES Bible Plugin Data |
| ywemanifest | Yahoo! Widgets Manifest Data |
| ywl | YoWindow Landscape Data |
| yxbe | Alteryx Designer Browse Everywhere Data |
| yxdb | Alteryx Designer Database |
| yxft | Alteryx Designer Field Types Data |
| yxi | Alteryx Designer Packaged Tool Data |
| yxlang | Alteryx Designer Localization Data |
| yxlc | Alteryx Designer License Data |
| yxmc | Alteryx Designer Macro Data |
| yxmd | Alteryx Designer Workflow Data |
| yxwg | Alteryx Designer Workflow Group Data |
| yxwv | Alteryx Designer App Values Data |
| yxzp | Alteryx Designer Packaged Workflow Data |
| z1 | Z-machine Z-code File |
| z2 | Z-machine Z-code File |
| z2s | SATURN Suite Zones to Sectors Data |
| z3 | Z-machine Z-code File |
| z32 | ZAR32 Saved Progress Data |
| z3l | ZW3D Part Library |
| z4 | Z-machine Z-code File |
| z5 | Z-machine Z-code File |
| z6 | Z-machine Z-code File |
| z64 | N64 ROM Image Mr. Backup Z64 |
| z7 | Z-machine Z-code File |
| z8 | Z-machine Z-code File |
| z80 | ZX Spectrum Emulator Snapshot Z80 |
| zak | Carlson Survey Coordinate Data |
| zal | SVAL Backup Data |
