Rejectable Conditions—The locations of all indications
having amplitudes greater than the 0.5 in. [13 mm] line given
in 15.3.6, when amplitude three times (machined surfaces) or
six times (cast surfaces) shall be marked on the casting surface.
The boundary limits of the indication shall be determined by
marking a sufficient number of marks on the casting surfaces
where the ultrasonic signal equals one half the reference