Projection
Projection is any part of the helmet, internal or external, that extends beyond the faired surface.
Source
16 CFR § 1203.4
Scoping language
Basic plane means an anatomical plane that includes the auditory meatuses (the external ear openings) and the inferior orbital rims (the bottom edges of the eye sockets). The ISO headforms are marked with a plane corresponding to this basic plane (see Figures 1 and 2 of this part).