Parse XML against Crossref Schema
Schema declarations in your XML
This test parser requires that the schema location be present in your schema declaration, for example:
<?xml version="1.0" encoding="UTF-8"?>
<doi_batch version="4.3.3" xmlns="http://www.crossref.org/schema/4.3.3"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.crossref.org/schema/4.3.3 http://www.crossref.org/schemas/crossref4.3.3.xsd">
To use other versions of the schema simply replace the 4.3.3 accordingly. Schema details are available in Crossref Help.