HTML and CSS Reference
In-Depth Information
sessiOn 9.1 visUAL OveRvieW
The
XML prolog
is the first
line of an XML document
that indicates that document
is written in XML.
The DOCTYPE or DTD
indicates the XML vocabulary
used in the document and
defines the syntax rules of the
language.
The
default namespace
indicates the default XML
vocabulary for elements and
attributes in the document.
In an XHTML document,
every non-empty element
must have a closing tag.
