5.1. The Role of XML Validation

XML achieves interoperability by rigorously enforcing certain rules about what may and may not appear in an XML document. With a few very small exceptions, a conforming processor can process any well-formed XML document and can identify (and not attempt to process) malformed documents. This ensures a high degree of interoperability between platforms, parsers, and programming languages. You don't have to worry that your parser won't read my document because yours was written in C and runs on Unix, while mine was written in Java and runs on Windows.

Fully maintaining XML correctness normally involves two redundant checks on the data: