SGML

Standard Generalized Markup Language

In short

A fine-grained way to store records and fields, but also elements and sub-elements; used for wrapping Database contents and for representing Text (formatted) and its constituent text objects; a precursor of both HTML and XML.

item info
types Markup
preferred ⚠️ under conditions
extensions .xml
related formats CSS, HTML, JavaScript, JSX, Markdown, TeX, XHTML, XML, XSLT
wikipedia SGML

See also