(Refer to figure 54, point 4) The thinner outer magenta circle depicted around San Francisco International Airport is
the outer segment of Class B airspace.
an area within which an appropriate transponder must be used from outside of the Class B airspace from the surface to 10,000 feet MSL.
a Mode C veil boundary where a balloon may penetrate without a transponder provided it remains below 8,000 feet MSL.