Here's a link to a site about it: http://clickit.go2net.com/search?po.../sutras/infinite_life/infinite_life_sutra.htm
On the link you can click on "dharma-ending age" for a definition. Looks like it's more of a process.
It is a prophecy, he wasn't too specific about when it would occur, remember in India they are used to thinking about periods of time in the trillions of years. Most buddhists tend to think that this is the Dharma ending age. You can ask aroud here: http://www.lioncity.net/buddhism/index.php
Yeah, it's great. Gives one hope for the species. Thanks for the link, I didn't look properly the first time.