Lee Passey wrote:
For review (and because I am a pendant), the pertinent named entities are:
‘ - left single quotation mark ’ - right single quotation mark “ - left double quotation mark ” - right double quotation mark ' - apostrophe (valid XML character entity, but /not/ valid HTML)
It should be noted, as Mr. Adock did, that "The apostrophe is different from the closing single quotation mark (usually rendered identically but serving a different purpose)." For the greatest flexibility, apostrophes should be encoded as ' and not ’. Examples might be: "Texas hold 'em" or "that can't be done." Double/single swapping will look really weird if you hadn't encoded the apostrophe correctly.
I'm not sure I see the value in marking up apostrophe as ' if you're a fan of curly quotes. You'd still have to go through and replace them with right single quotation marks somewhere in your workflow, as ' is the vertical single quote at U+0027.