Typographic elements are used to specify the format of marked
Typical renderings for idiomatic elements may vary between user
agents. If a specific rendering is necessary -- for example, when
referring to a specific text attribute as in "The italic parts are
mandatory" -- a typographic element can be used to ensure that the
intended typography is used where possible.
NOTE - User agents may support some typographic elements not
included in this specification, as they have been deployed to some
extent. The <STRIKE> element indicates horizontal line through the
characters, and the <U> element indicates an underline.