IPP 3D Printing Extensions v1.1 (3D) has been approved as PWG Candidate Standard 5100.21-2019.
This specification defines an extension to the Internet Printing Protocol and IPP Everywhere that supports printing of physical objects by Additive Manufacturing devices such as 3D printers.
https://ftp.pwg.org/pub/pwg/candidates/cs-ipp3d11-20190329-5100.21.pdf