This is a new frequency which is actually replacing the BOSOX47 secondary freq. The previous alternate freq was 135.55, and 127.97 has been online for a month or so now. Both of these are sited on the east side of the sector (Melrose area?) as opposed to the normal freqs which are out in Woodstock (near BDL) or on Mt. Tom.
These alternate freqs are used pretty infrequently but when there is a large area of weather south and west of Boston, using a transmitter closer to Boston makes a big difference as there is always a few departing a/c from Logan that have trouble receiving ZBW primary freqs when below 14,000ft.