I need a way to detect the timezone of a given date object. I do NOT want the offset, nor do I want the full timezone name. I need to get the timezone abbreviation.

For example, GMT, UTC, PST, MST, CST, EST, etc...

Is this possible? The closest I've gotten is parsing the result of date.toString(), but even that won't give me an abbreviation. It gives me the timezone's long name.