Comment by tannhaeuser
3 years ago
> Then we said it's too verbose. We named some subsets XML, HTML, XSLX
If anything, XML as an SGML subset is more verbose than SGML proper; in fact, getting rid of markup declarations to yield canonical markup without omitted/inferred tags, shortforms, etc. was the entire point of XML. Of course, XML suffered as an authoring format due to verbosity, which led to the Cambrian explosion of Wiki languages (MediaWiki, Markdown, etc.).
Also, HTML was conceived as an SGML vocabulary/application [1], and for the most part still is [2] (save for mechanisms to smuggle CSS and JavaScript into HTML without the installed base of browsers displaying these as content at the time, plus HTML5's ad-hoc error recovery).