| yobj | Yukes 3D Object |
| ypp | GNU Bison Source Code |
| ys | Y86 Assembler Source Code |
| ysp | BYOB Sprite |
| yxx | GNU Bison Source Code |
| yy | GNU Bison Parser |
| zanebug | Zanebug Data |
| zasm | Zero Compiler Assembly Source Code |
| zbj | Visual Zero Object |
| zbl | Zeble Markup Data |
| zcls | Zero Compiler Class Data |
| zcos | Scilab XML Diagram |
| zef | Unity Pro Full Application Exchange Data |
| zem | Zope External Editor File |
| zep | Zephir Source Code |
| zepto | Zepto JS Script |
| zexp | Zope Binary Export File |
| zf3d | Flare3D Model |
| zfd | ABC Zeroadic Functions Data |
| zfrm | Zero Form Designer Data |
| zh | Netscape Navigator Java Classes File |
| zodb | Zope Object Database |
| zog | Zoggy Data |
| zp | Zepto Source Code |
| zpd | ABC Zeroadic Predicate Data |
| zpk | Zend Studio Application Package |
| zpt | Zope Page Template |
| zrf | Zillions Rules |
| zrp | RapidPLUS Application Package |
| zrx | ZOC REXX Script |
