In this page you can check the validity of your XML Schema (XSD) file. The library used in this page is jaxp, Java API for XML Processing, version 1.4, from Java(TM) SE Runtime Environment (build 1.7.0_06-b24).
XML Schema or Relax NG schema also allows you to embed Schematron rules.
For Schematron validations you can also select the validation phase.
I didn't realize that the was actually reading the XSD from my hard drive from the same subdir as the XML file and validating. Just an FYI, if you use nested schemas and refer other schema using relative path such as foo\abc.xsd, make sure that you use forward slash(/) instead of backward slash (\) when validating in NPP Xml Tools plugin.
If you use backward slash, it gives schema parsing error but forward slash works fine.
Write Line("Validating doc1"); bool errors = false; doc1. After the change, orders will then refer to a customer that does not exist, so the XML document will no longer validate.