lucy24 - 3:35 am on Jan 4, 2013 (gmt 0)
Possibly we are working from different lexicons.
"semantic markup" = what it means, what its function is
"presentational markup" = what it looks like
<em> = emphatic. Currently rendered by all browsers as <i>, at least in English.
But the concept of "emphasis" can also be expressed as:
-- plain text when body text is italic: popular a few centuries ago
-- small caps: ditto
-- katakana instead of hiragana if text is Japanese
-- spaced-apart letters when text is in fraktur or greek
-- boldface when text is greek; also in any script that doesn't use italics
-- bold italics when text is italic representing a short quotation
... et cetera. I'm restricting myself here to examples I've personally seen and in most cases used.