"Private Space" Opcode Allocation Table
| Opcode(s) | Company | Contact | Description |
| 0x4000 | Microsoft | Weihai Chen | Used by Microsoft in Win 2000 (and presumably also in their Win 95 and 98 IPP clients) |
| 0x4001-0x400C | Easy Software Products | Michael Sweet | Used in the CUPS Unix implementation of IPP. For details see http://www.cups.org/cups-ipp-20000104.html |
| 0x400D-0x400F | Easy Software Products | Michael Sweet | move-job operation + future expansion. For details see CUPS Implementation of IPP |
| 0x4010 | Peerless Systems Imaging Products | Kris Henderson | |
| 0x401A-0x4025 | Novell | Ted Tronson | |
| 0x4026 | Xerox | Peter Zehler | |