[libvirt] Versioning/Compatibility in the XML schemas

Out of curiosity, seeing that we doing modifications to the XML schema all the time, there does not seem to be some sort of version identifier in the XML schemas. If I take the recently merged patch for DHCP options, for instance, suppose virt-manager would add support for it in its GUI. How would such a network XML definition be interpreted by older libvirt versions? Is it supposed to ignore elements it doesn't know or do we have an implicit requirement of "always use the latest versions together"? -- Pieter Hollants <pieter(a)hollants.com&gt;