2010 ADA Standards for Accessible Design Pocket Guide

Mezzanine.

An intermediate level or levels between the floor and ceiling of any story with an aggregate floor area of not more than one-third of the area of the room or space in which the level or levels are located. Mezzanines have sufficient elevation that space for human occupancy can be provided on the floor below. [S.H. 3.5 Mezzanine]