DOT NET RULES

Let’s start by saying this:

If an XML document is valid then by default it is well-formed. Unfortunately the reverse is not always true.  Well-formed XML documents do not necessarily have to be valid.

According to XML specification we must follow certain rules to create XML documents. Some of them are

• having exactly one root element
• close all opening tags
• using single/double quotes for attribute values

If an XML document abides by these rules, it is a well-formed XML document.

DTD is primarily used for the expression of a schema via a set of declarations that conform to a particular markup syntax. It describes the structure and content of a document, in terms of constraints on the structure of that document. In DTD we find information such as:

• the parent-child relationship details
• attribute lists
• data type information
• value restrictions

If a document is well formed and also follows the rules in its associated DTD, it is a valid XML document.