Next Tuesday, Princeton commissioners will talk about annexation — forced annexation, to be precise. Fortunately, Mayor Don Rains seems to know when such annexation is justified and when it is not.In our view, one the mayor appears to share, forced annexation is justified when people who live just outside of town benefit from their proximity to town. Perhaps their property values are higher because they live to close town. Perhaps they’re close to shops and services that choose towns because they are towns. (Those criteria certainly came into play when Smithfield annexed West Smithfield many years ago now). Or perhaps, as is the case in Princeton, police patrol your neighborhood en route to a neighborhood that’s actually in town.In Princeton, Mayor Rains seems to know these things, which ought to make next week’s discussions black and white, no shades of annexation gray. Either folks benefit from living near Princeton, or they don’t. If they do, it’s OK to annex. If they don’t, it’s not.It’s that simple.