ONIX 2.1 - thoth-pub/thoth GitHub Wiki
ONIX is an XML-based standard for representing and communicating book industry product information in electronic form. Even though already sunset at the end of December 2014, ONIX 2.1 is still current in certain contexts.
Archived specs of ONIX 2.1 can be downloaded on EDItEUR.
ONIX 2.1 records can be imported in: