| xyd | XYPad Drawing Document |
| xyp | XyWrite III Plus Document |
| xyw | XyWrite IV Document |
| xzfx | ZipLogix ZipForm Transaction |
| xzip | Hungarian Tendering System Document |
| yak | KayakFoundry 3D Design Documen |
| yang | YANG Designer Document |
| yaodl | SGI PowerFlip YAODL 3D Image |
| yar | Yar Scene |
| ybk | Microsoft Encarta Yearbook |
| ydb | Yutori 7 Document |
| ydd | YANG Designer Document |
| ydl | SGI PowerFlip YAODL 3D Image |
| yes | Quick Bible Document |
| ygf | Y Graph Format |
| yka | Yenka Model |
| ymap | MindGenius v1 Document |
| z3d | ZModeler 3D Model |
| z3n | ZW3D Neutral Format File |
| zabw | AbiWord Gzip Compressed Document |
| zbr | ZBrush Document |
| zcl | Zoner Callisto Clipart Document |
| zcn | OmniPage Language Data |
| zdg | ZiffNet ZView Compressed Document |
| zdl | Avery DesignPro Label |
| zdx | Avery DesignPro Clipart Index |
| zed | Compressed GEDCOM Document |
| zed | ZX-Edit Document Block |
| zgl | Compressed XGL Document |
| zgt | Oren-made Scientific Document |
| zhp | Compressed Swiftview Document |
| zhtml | Secure IE Zipped HTML |
| zir | C.a.R. Figure |
| zjs | Zenographics ZjStream SuperPrint Zj Stream |
| zno | Zinio Reader Magazine |