XML declaration Root element Elements Attributes Empty elements Comments CDATA sections Entity references

Case sensitivity Well-formed nesting Quoted attributes Escaping ampersand Escaping less-than Whitespace preservation xml:space Unicode content

Default namespace Prefixed namespace Namespace declaration Qualified element names Qualified attributes Namespace scope Multiple vocabularies Namespace URI identity

DOCTYPE declaration Element declaration Attribute declaration Internal entity External entity risk ID attribute concept DTD validation concept Mixed content

Schema namespace Element type Simple type Complex type Sequence Choice Occurrence constraints Attribute requirement

XPath selection XSLT transform concept DOM parsing concept SAX streaming concept XML serialization Canonicalization concept XXE prevention Content-Type application/xml