Vocabulary

This specification uses the words below with the precise meaning given.
Representation
The encoding of information for interchange. For example, HTML is a representation of hypertext.
Rendering
The form of presentation to information to the human reader.

Imperatives

may
The implementation is not obliged to follow this in any way.
must
If this is not followed, the implementation does not conform to this specification.
shall
as "must"
should
If this is not followed, though the implementation officially conforms to the standard, undesirable results may occur in practice.
typical
Typical rendering is described for many elements. This is not a mandatory part of the standard but is given as guidance for designers and to help explain the uses for which the elements were intended.

Notes

Sections marked "Note:" are not mandatory parts of the specification but for guidance only.

Status of features

Mandatory
These features must be implemented in the rendering. Features are mandatory unless otherwise mentioned.
Optional
Standard HTML features which may safely be ignored by parsers. It is legal to ignore these, treat the contents as though the tags were not there. (e.g. EM, and processing instructions) . Authors should be awarethat these features may be ignored by some applications.
Proposed
The specification of these features is not final. They should not be regarded as part ofthe standard, but indicate possible directions for future versions.
Obsolete
Not standard HTML. Parsers should implement these features as far as possible in order to preserve back-compatibility with previous versions of this specification.