Design ConstraintsWhen designing the HTML document type, consideration was given to
a certain simplicity in order to allow many browsers and hopefully
editors to be developed on many platforms.
Lack of nestingMany text editing systems (Microsoft Word, The NeXT text object, the
Mac text object, etc) handle text in a variety of styles but do not
have any concept of nestable structure in the SGML sense.
The constraint here is therefore that HTML be able to be mapped into
a sequence of paragraphs of styled text, and that if that text is
edited that the editor should be able to map the sequence of styles
back onto a sequence of elements in a well-defined way. This allows
some limited trivial nesting (eg LI within UL) but no general nesting,
as a finite and small set of styles is used. In particular, the styles
are not parameterized by the nesting level.
Logical MarkupIt is required that HTML be a common language between all platforms.
This implies no device-specific markup, or anything which requires
control over fonts or colors, for example. This is in keeping with
the SGML ideal.