The XML Validation (eXtensible Markup Language) checks a document in XML language if it is well formed and it is adjusted to a defined structure. A well formed document follows the basic rules of XML established for the design of documents. Moreover a valid document respects the rules dictated by a DTD or XML schema. In addition extended tools are available such as OASIS CAM standard specification that provide contextual validation of content and structure that is more flexible than basic schema validations. xmllint --valid --noout example.xml