XML Structure

Structurally, an XML document is an entity that "owns" a set of other XML nodes. Although it must have a root element, you can optionally include any of the following nodes.

• Declarations

• Processing instructions

• Elements

• Character data

Elements are the essential individual components of XML content. They contain both the data and the markup that describes that data. The ability to group and nest user‑defined elements within one another provides much of the extensibility of XML. The rest is provided by allowing you to define the rules by which the XML tree structure is to be interpreted.

All languages have rules to which users must adhere in order to be understood. In spoken languages, this means:

• Including the appropriate subjects, objects, and verbs

• Using correct vocabulary

• Applying the correct grammatical rules