Abbreviated NHZ.  The space within which the level of the direct, reflected or scattered radiation may exceed the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE.

Abbreviated NOHD.  The distance along the axis of an unobstructed laser beam from a laser, a fiber end, or connector to the human eye beyond which the irradiance or radiant exposure is not expected to exceed the applicable MPE.