According to NFPA 101®, Life Safety Code®, an Assembly Occupancy includes all buildings or portions of buildings used for the gathering of 50 or more persons for purposes such as eating, drinking, entertainment, or worship. A restaurant's primary function is for people to gather for eating and drinking. When its occupant load exceeds the threshold of 49 persons, it is classified as an Assembly Occupancy. This classification triggers specific life safety requirements appropriate for a large number of people in a single space.

A. Business: This classification applies to occupancies used for the transaction of business, such as offices, not for public gatherings for dining.

B. Kitchen: A kitchen is a functional area within an occupancy that has its own specific hazards and protection requirements, but it is not a standalone occupancy classification.

C. Mercantile: This classification is for the display and sale of merchandise, like a department store. A restaurant's primary purpose is on-premises consumption, not retail sales.

1. NFPA 101®, Life Safety Code®, 2021 Edition. Section 6.1.3.1, "Assembly Occupancies," states: "Assembly occupancies include, but are not limited to, all buildings or portions of buildings used for gathering together 50 or more persons for such purposes as deliberation, worship, entertainment, eating, drinking, amusement, or awaiting transportation."

2. SFPE Handbook of Fire Protection Engineering, 5th Edition. Chapter 53, "Occupancy Fire Hazards," Section 53.4.3, "Assembly Occupancies." This section discusses the characteristics of assembly occupancies as defined by model codes like NFPA 101, reinforcing the 50-person threshold for places like restaurants. (DOI: 10.1007/978-1-4939-2562-453)

3. Oklahoma State University, School of Fire Protection and Safety Engineering Technology. Courseware for FPST 3333, "Fire Protection Systems." Lecture materials on Occupancy Classification consistently use a restaurant with an occupant load of 50 or more as a primary example of an Assembly Occupancy based on NFPA 101 definitions.