A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | #
| Y | YACC Grammar |
| Y | Amiga Yabba Compressed Archive File |
| Y | Desktop Color Separation Specification Yellow Layer |
| Y01 | Paradox Secondary Index (can be 01 to 09) |
| Y64 | Commandos 2 Game Mission |
| YAL | Arts & Letters Clipart Library |
| YBK | Microsoft Encarta Yearbook |
| YEL | Yellow color separation |
| YG0 | Paradox Secondary Index (can be YG0 to YG9) |
| YMG | Yahoo! Messenger File |
| YPS | Yahoo! Messenger File |
| YUV | Color Space Pixel Format |
| YZ | Yac Compressed Archive File |
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