I'll pile on- a 127.5mm spindle would be correct for an early-'80's triple crank, such as a Sugino Aero Tour, on a mountain bike where the cranks would need to be further apart to clear the chainstays. For a Shimano Alivio triple, the spindle length would be 115mm since the crankarms are angled from the spindle to the pedal end, while a Vuelta Pista is a single ring crank needing only a 107mm or 110mm spindle.

The great thing about square-taper bottom brackets and spindles is that the large number of available lengths gave bike builders a lot of flexibility in spec'ing the configuration of the crankset. Current "two-piece" cranks lock the builder into one set of dimensions, ignoring the different requirements of riders and applications. Humph...