(though the XML specification itself makes no such claim). JSON, YAML, and S-Expressions are frequently proposed as simpler alternatives (see Comparison of data serialization formats) that focus on representing highly structured data rather than documents, which may contain both highly structured and relatively unstructured content. However, W3C standardized XML schema specifications offer a broader range of structured XSD data types compared to simpler serialization formats and offer modularity and reuse through XML namespaces. See also List of XML markup languages List of XML schemas Extensible programming CAMX Comparison of data-serialization formats Binary XML EBML WBXML XML Protocol Notes References Further reading Annex A of ISO 8879:1986 (SGML) External links W3C XML homepage XML 1.0 Specification Retrospective on Extended Reference Concrete Syntax by Rick Jelliffe XML, Java and the Future of the Web (1997) by Jon Bosak http://validator.w3.org/ The Official [W3C] Markup Validation Service The XML FAQ originally for the W3C's XML SIG by Peter Flynn Application layer protocols Articles with example code Bibliography file formats Computer file formats Data modeling languages Data serialization formats Markup languages Open formats Presentation layer protocols Technical communication World Wide Web Consortium standards