10.4 HTML and SGML

1.	HTML is based on the Standard Generalized Markup Language (SGML) that is an international standard (ISO8879) [2] for defining system-independent methods for representing text in electronic form.
2.	In particular, it is a standard through which electronic markup text can be described, i.e. it is used to describe markup languages.
3.	A markup is defined as any means of making explicit an interpretation of a text.
4.	E.g. in the English language, the following can be regarded as markups:

	a)	Punctuation marks.
	b)	Use of capitalization.
	c)	Spaces between letters.
	d)	etc.

10.4 HTML and SGML

5.	A markup language is a set of markup conventions used to encode text.
6.	To define a markup language, the following need to be determined:

	a)	What markups are allowed.
	b)	What markups are required.
	c)	How markup is distinguished from text.
	d)	And what the markups mean.

7.	SGML is used to define the first three requirements above and language documentation should be used for the last.
8.	Each markup language defined in SGML is called an SGML application.
9.	HTML is a markup language defined in SGML, thus an SGML application.