Ryan Gomes and His Contract: How does it work?

Some here have talked about trading Gomes as a potential expiring or as a potential contributor to a team who wants to win now. I'm not saying he'd help a team do that, but it's a plausible scenario that he could help, or at least, that some GM might THINK he could help contribute to winning (see examples: Foye, Randy; Miller, Mike). Could those who know more about the particulars of his team option explain how it works? Is it a possible expiring contract that's unique in that it can become an expiring DURING the offseason (i.e., an expiring contract that can be obtained AFTER the trade line)? Or, would his contract expire before the moratorium ends and make him an asset in a trade only if a team wanted to acquire Ryan Gomes the player?