| 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 |
| xds | LcdStudio Design |
| xec | Afaria XEC File |
| xed | Kinect Studio Recording |
| xef | X-Genics eManager Form Data |
| xej | Microsoft Expression Encoder Job |
| xel | Microsoft Expression Encoder Live Encoding |
| xem | Sybase PowerDesigner Extension File |
