XML Schema

XML Schema, published as a W3C Recommendation in May 2001, is one of several XML schema languages. It was the first separate schema language for XML to achieve Recommendation status by the W3C.

Like all XML schema languages, XML Schema can be used to express a schema: a set of rules to which an XML document must conform in order to be considered 'valid' according to that schema. However, unlike most other schema languages, XML Schema was also designed with the intent that determination of a document's validity would produce a collection of information adhering to specific data types. Such a post-validation infoset can be useful in the development of XML document processing software, but the schema language's dependence on specific data types has provoked criticism.
An XML Schema instance is an XML Schema Definition (XSD) and typically has the filename extension ".xsd". The language itself is sometimes informally referenced as XSD. It has been suggested that WXS (for W3C XML Schema) is a more appropriate initialism though this acronym has not been in a widespread use and W3C working group rejected it. XSD is also an initialism for XML Schema Datatypes, the datatype portion of XML Schema.
DocFamily supports XML Schemas to validate data entered through its DocWrite HTML XFORMS implementation. In addition, XML Schema is also used to validate business data begin formatted with DocBase.