Hi -- I'm the somone mentioned above. Nice table!
I'm fairly sure the Google documentation is wrong and IE 7 does
not support ' entity in HTML docs. Unfortunately (fortunately?) I don't have IE7 available to test. But a quick search for "IE7 apos" yields lots of chatter about the lack of support.
I agree with your sentiment that ' is widely supported and should be included. But I also think this is a good opportunity to provide some valuable extra information. After all, most people looking up character entities are creating web pages and, for now, most of them care about IE7 compatibility. One option might be to make ' show as a link that, when clicked, pops up more detail. Or maybe better woudl be to include a column indicating the standard that introduced the entity? (as does the table at
https://secure.wikimedia.org/wikipedia/en/wiki/List_of_XML_and_HTML_character_entity_references). Add some color coding for different values in that column, and ' pops out visually as an outlier.
Cheers!