Entry

What is a well-formed, validated XML document?

Nov 21st, 2000 06:58
Michael Claßen,

A document has to follow a set of rules to qualify as an XML document.
Most importantly the opening and closing tags have to be properly
nested, overlapping is not allowed. A document with properly nested tags
is said to be "well-formed".
XML has facilities for specifying the structure of XML documents further
called Document Type Definitions (DTDs), and its newer companion XML
Schema. Using these a specific vocabulary for a certain subject area can
be defined. A DTD or Schema defines the set of allowed tags,
their valid nestings, their cardinality, and where text is allowed to
appear. An XML document which conforms to its DTD or Schema is said to
be "valid".
For more information on DTDs see http://webreference.com/column10/, XML
Schema is explained in http://webreference.com/column21/.