Standard Generalized Markup Language (SGML)

What is a Standard Generalized Markup Language (SGML)?

The Standard Generalized Markup Language (SGMl) as defined in ISO8879, is a language for defining markup languages. HTML is one such "application" of SGML.

An SGML application consists of several parts:

• The SGML declaration. The SGML declaration specifies which characters and delimiters may appear in the application.
• The document type definition (DTD). The DTD defines the syntax of markup constructs. The DTD may include additional definitions such as numeric and named character entities.
• A specification that describes the semantics to be ascribed to the markup. This specification also imposes syntax restrictions that cannot be expressed within the DTD.
• Document instances containing data (contents) and markup. Each instance contains a reference to the DTD to be used to interpret it.