PWG Standard 5100.12-2015: IPP 2.0, 2.1, and 2.2 has been approved. This specification defines the IPP 2.0, 2.1, and 2.2 protocol versions. Each version defines a minimum set of supported IPP extensions to simplify development and interoperability of IPP Client and Printer implementations.
The published standard can be found at:
Michael Sweet, Senior Printing System Engineer