<marquee>
This text should be scrolling right-to-left in Internet Explorer browsers, but is not.
<span>
This text should have a yellow background, but doesn't.
<blink>
IIRC, the span tag isn't disabled, but the "style" attribute (the only one that's really useful in 'span') is. Too bad, since there are many things that can only be done with the style attribute including setting precise font sizes [generally annoying unless it's necessary to make text fit a fixed-sized item, in which case its lack is annoying] and controlling background colors for text outside of tables.
< embed src="http://bertino.tierranet.com/disney/midi/smlworld.mid" Autostart="true">
I put an extra space between the < and embed