Just what constitutes a "play"? Or, phrased another way, when is the plays counter incremented?

Does it increment when a song has played through, from start to finish (regardless of interruptions due to turning the empeg off)? Does it increment once the song has started, regardless of whether you subsequently skip it? What if you're in the middle of the song, and re-start it? Does that count as another play?

I looked in the FAQ, and searched on the board, but didn't find the answer. Maybe I wasn't using the right search terms...

Cheers,