XML - thoth-pub/thoth GitHub Wiki
XML is Publication Type in Thoth.
Extendable Markup Language (XML) is a markup language designed for both human-readable and machine-readable documents. XML is defined as a syntax, without fixed vocabulary. The currently widely used version of XML is XML 1.0 as defined by the W3C. XML is also used as syntax for ONIX 3.0 and MARCXML metadata records.