A document file format is a text or binary file format for storing documents on a storage media, especially for use by computers.There currently exists a multitude of incompatible document file formats.
Examples of XML-based open standards are the ISO/IEC standards OpenDocument (ISO 26300:2006) and the Strict and Transitional versions of Office Open XML (ISO 29500:2008). Another example is DocBook which is used for writing structured documentation such as manuals, books, technical guides, and then processed with stylesheets/toolchains to generate HTML, PDF, EPUB, man pages, etc. XHTML, an earlier document file format over time became part of HTML5.