Validates the XML string/file against the specified XSD string/file.
XSD files are "XML Schemas" that describe the structure of a XML document.
The validator checks for well formedness first, meaning that your XML file must be parsable using a DOM/SAX parser, and only then does it validate your XML against the XML Schema.
What I am looking for is an XML tool that will help in XSD modeling and development of schemas. NET developer XMLFox I have to tell you, I nearly gave up looking for an XML Editor that edited XML like a spreadsheet. Having said that, you should consider using a similar business model as Heidi SQL.
I came across XMLFox and it looks very interesting and substantially free than any other expensive XML-editing stuff. You have something that is as useful to me as Heidi SQL.