Sorry, I don't understand your question. If its not jdbc, its a ConnectionFactory not a DataSource. A particular ConnectionFactory is going to have only one of NoTx, local tx, or xa support configured. You can put as many connection factory configurations in one file as you want.
There's not much documentation for the format. You can look at the samples such as firebird-ds.xml and look at the xsl that processes it, ConnectionFactoryTemplate.xsl. The source is in the connector module, connector/src/resources/stylesheets.