| xbb | DVIPDFMx Output File |
| xbd | Xilinx Xilinx Board Description Format File |
| xbdr | Darkroom Booth Template |
| xbf | XAML Binary File |
| xbin | RegSupreme Pro Licence Data |
| xbn | Xnick Nick Backup Data |
| xc3 | Cast3D 3D Scene Data |
| xcbr | Sonic Workbench XPath Routing Rules |
| xccolortheme | Xcode Color Theme Data |
| xcd | WarpIN Data File |
| xcn | GenePattern XCN Data |
| xco | Xilinx CORE Generator Log |
| xcp | Casio ClassPad 300 Exported ClassPad |
| xcs | TBX eXtensible Constraint Specification |
| xcsl | CineStyle Color Correction Data |
| xcsr | Oracle UCM Content Folio XML |
| xcst | Oracle UCM Content Folio Template |
| xcworkspace | Xcode Workspace Data |
| xdat | XMVB Data File |
| xdb | Norton Antivirus Update |
| xdd | XFIT XDD Format Data |
| xdelta | Xdelta Binary Differential Data |
| xdf | TunerPro Definition File |
| xdl | Expert Definition Language Document |
| xdm | Oracle BI Publisher Data Model |
| xdmz | Oracle BI Publisher Compressed Data Model |
| xdna | DNA Strider Sequence Data |
| xdo | Oracle BI Publisher Report Definition |
| xdoz | Oracle BI Publisher Compressed Report Definition |
| xdrz | Oracle BI Publisher Folder Data |
