| x3p | XML 3D Surface Profile |
| x3s | X3S Data |
| x40 | XTreeGold for Dos Help Data |
| x50 | XTreeGold for Dos Help Data |
| x60 | XTreeGold for Dos Help Data |
| x61 | Lenovo ThinkPad X61 Bios Update |
| x6a | Yamaha MOXF Backup Archive |
| x70 | XTreeGold for Dos Help Data |
| x7a | Yamaha MONTAGE Backup Data |
| x7b | Yamaha MONTAGE Bulk Data |
| x80 | XTreeGold for Dos Help Data |
| x83 | GAEB DA XML Data File |
| x90 | XTreeGold for Dos Help Data |
| xa | Chiron NRG Exported Dictionary |
| xa0 | XTreeGold for Dos Help Data |
| xa2 | eXtendable Wad Editor XA2 Data |
| xa30 | eXtendable Wad Editor XA30 Data |
| xaa | XML Audit Data |
| xab | Microsoft Mail Addressbook Data |
| xac | GnuCash Data |
| xac | XMetaL Author Customization File |
| xadd | Microsoft Expression Web Add-in |
| xades | XAdES Signature |
| xadml | XML-Based Application Description Information |
| xaf | Autodesk 3D Studio MAX XML Animation |
| xaf | Cal3D XML Animation |
| xaf | IMVU Animation |
| xaiml | XAIML Chatterbot Database File |
| xao | SALOME Geometry XAO Data |
| xappl | Turbo Studio XML Application Configuration |
