XProc is an XML transformation language for processing documents in pipelines: chaining conversions and other steps together to achieve the desired results.
Ideas for something, some programming language, for processing were there right from the beginnings of XML, at the end of the twentieth century.
The only two currently available as open source products that implement the full 1.0 standard are XML Calabash[5] and MorganaXProc.
This was based on a non-XML syntax which didn’t raise a lot of support from the community.
In June 2017 the XProc Next Community Group[3] was founded and started working on a new version, now completely XML based.