Validating XML Documents Against a Schema
A Valid XML document is a Well-Formed XML document that also conforms to the rules of a schema that defines the legal elements of an XML document. The schema type can be: XML Schema, Relax NG (full or compact syntax), Schematron, Document Type Definition (DTD), or Namespace-based Validation Dispatching Language (NVDL).
The purpose of the schema is to define the legal building blocks of an XML document. It defines the document structure with a list of legal elements.
The  Validate function ensures that your document is compliant with the rules
            defined by an associated DTD, XML Schema, Relax NG, or Schematron schema. XML Schema
            or Relax
            NG schema also allows you to embed Schematron rules. For Schematron validations you
            can also
            select the validation phase.
Validate function ensures that your document is compliant with the rules
            defined by an associated DTD, XML Schema, Relax NG, or Schematron schema. XML Schema
            or Relax
            NG schema also allows you to embed Schematron rules. For Schematron validations you
            can also
            select the validation phase.
         
