[Termtools] how to read syntax of higher-order rules

[Makoto Hamana]

Dear All,

I want to see the specification and the grammer of the syntax of
higher-order rules of the current TPDB like the older one
https://www.lri.fr/~marche/tpdb/format.html

I looked at

http://termination-portal.org/wiki/TPDB

and it says "for versions from 7.* onwards (XML format): xtc.xsd, already part of the TPDB".

How can I read xtc.xsd? The plain XML file is hard to read.
Is there some viewer for this?

Best Regards,
Makoto