The distribution contains RELAX NG Compact schema files. These are found in the distribution at:

    xml/schema/metaproxy.rnc
   

If Trang is found on your system, then the Metaproxy build system will convert these to:

    xml/schema/metaproxy.rng
    xml/schema/metaproxy.xsd
   

These schema can then be used to verify or debug the XML structure of Metaproxy configuration files. For example, using the utility xmllint, syntax checking is done like this:

    xmllint --noout --schema xml/schema/metaproxy.xsd etc/config-local.xml
    xmllint --noout --relaxng xml/schema/metaproxy.rng etc/config-local.xml
   

(A recent version of libxml2 is required, as support for XML Schemas is a relatively recent addition.)

You can of course use any other RELAX NG or XML Schema compliant tool that you wish.