The XML Schema language, sometimes used in connection with representing data for storage in computers, contains built-in primitive datatypes, date and dateTime, which do not allow a year zero, and designate years BC as negative numbers.

newer XML namespace-aware schema languages ( such as W3C XML Schema and ISO RELAX NG ) have largely superseded DTDs.

* XML Schema, also referred to as XML Schema Definition ( XSD ), has achieved Recommendation status within the W3C, and is popular for " data oriented " ( that is, transactional non-publishing ) XML use because of its stronger typing and easier round-tripping to Java declarations.

* XML Schema Language Comparison-Comparison to other XML Schema languages.

* XML Schema ( W3C )

* XML Schema

* XML Schema is a language for providing and restricting the structure and content of elements contained within XML documents.

* XML Schema

After an abortive attempt to create a version 1. 1 in 2001, the XSL working group joined forces with the XQuery working group to create XPath 2. 0, with a richer data model and type system based on XML Schema.

( There are also W3C XML Schema + Schematron and Document Type Definition ( DTD ) versions of the schema available, but these are considered non-standard.

RELAX NG and W3C XML Schema forms of the XML version are available.

Originally motivated by a desire to provide a common syntax and behavior model between XPointer and XSLT, subsets of the XPath query language are used in other W3C specifications such as XML Schema and XForms.

A Document Type Definition ( DTD ) is a set of markup declarations that define a document type for an SGML-family markup language ( SGML, XML, HTML ).

* Definition of the XML document type declaration from Extensible Markup Language ( XML ) 1. 0 ( Fourth Edition ) on W3. org

WML documents are XML documents that validate against the WML DTD ( Document Type Definition )

* W3C XML Pipeline Definition Language is specified in a W3C Note.

* W3C XML Pipeline Definition Language Note

* Oracle's XML Pipeline Definition Language Controller Implementation Part of XML Developer's kit, no individual download

* XML Process Definition Language

Document Schema Definition Languages ( DSDL ) is a framework within which multiple validation tasks of different types can be applied to an XML document in order to achieve more complete validation results than just the application of a single technology.

Sometimes the adjective well-formed is used to contrast with valid: a valid XML document is one that is not only well-formed, but also conforms to the grammar defined in its own DTD ( Document Type Definition ).

* Channel Definition Format, an XML standard

The Document Type Definition ( DTD ) language, which is native to the XML specification, is a schema language that is of relatively limited capability, but that also has other uses in XML aside from the expression of schemas.

An XML Schema Definition ( XSD ) implementation of Version 2. 0 was released in September 2008.

It resulted in a Document Type Definition for a file containing the XML representation of entries in the LDAP data model, similar in spirit to LDIF.

EBML is not extensible in the same way that XML is, as the Document Type Definition must be known in advance.

* XML Process Definition Language ( XPDL ),

A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document ( for example, a webpage ) with a Document Type Definition ( DTD ) ( for example, the formal definition of a particular version of HTML ).

∠, the angle symbol in Unicode is List of XML and HTML character entity references | U + 2220

Berkeley DB is also used as the common name for three distinct products ; Oracle Berkeley DB, Berkeley DB Java Edition, and Berkeley DB XML.

DB XML is written in C ++ and supports multiple language bindings, including C ++, Java ( via JNI ), Perl and Python.

XHTML, which is an XML application, supports the HTML entity set, along with XML's predefined entities.

XQuery is an XML based database language ( also named XQL ).

XML is open, machine-readable and cross-platform data format widely used for interoperability among different IT systems.

A DTD is associated with an XML or SGML document by means of a Document Type Declaration.

( Notations declared in the DTD are also referencing external entities, but these unparsed entities are not needed for the validation of documents in the standalone mode of these parsers: the validation of all external entities referenced by notations is left to the application using the SGML or XML parser ).

However this behaviour is application-specific, and requires that the application maintains a catalog of known URNs to resolve them into the notations that have been parsed in a standard SGML or XML parser.

The XML DTD syntax is one of several XML schema languages.

In addition, documents for these XML schema languages have to be parsed separately, so validating the schema of XML documents in pure standalone mode is not really possible with these languages: the document type declaration remains necessary for at least identifying ( with a XML Catalog ) the schema used in the parsed XML document and that will be validated in another language.

In the example below, the XML document is declared with because it has an external subset in its document type declaration:

If the XML document type declaration includes any SYSTEM identifier for the external subset, it can't be safely processed as standalone: the URI should be retrieved, otherwise there may be unknown named character entities whose definition may be needed to correctly parse the effective XML syntax in the internal subset or in the document body ( the XML syntax parsing is normally performed after the substitution of all named entities, excluding the five entities that are predefined in XML and that are implicitly substituted after parsing the XML document into lexical tokens ).

However, many browsers do not check that an XML document conforms to the rules in the DTD ; they are only required to check that the DTD is syntactically correct.