That is exactly the type of intersection I meant, when I said it was NOT one of these. There are quite a few around Acton and Concord (the intersection is in Acton) and the "line" I believe they are referring to is the white line going parallel to the cross street just when you get to the front of the intersection. However, I have seen special markers for the bike sensor in some places (mostly in other states). Yes, it took a lengthy discussion on TE for a few of us to figure out what "bikes stop here on green" meant. But it's no different than "reverse curve" or other language things that are peculiar to MA.
I guess I could could call the Acton highway dept., but since this light crosses Rt. 2, it's probably controlled by the state highway dept. That might take a million years.