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A function code defines how a commercial lockset behaves: which side locks, whether the outside lever is rigid or free, and whether a key or a thumbturn controls it. You cannot order a commercial lock without choosing one. The ANSI/BHMA function names (Office, Classroom, Storeroom, Privacy, Passage, and a dozen more) are standardized in A156.2 for cylindrical locks and A156.13 for mortise locks, but each manufacturer also assigns its own catalog number. Schlage uses three letters such as ND53PD, Sargent uses a number such as 8205, and Corbin Russwin uses CL and ML numbers. This guide maps the most-used functions to what they do, which door they belong on, and the ANSI F-number that lets you substitute confidently across brands.

What a function code actually controls

The inside lever is the part the code rarely changes, because it must always retract the latch and allow exit without a key or any special knowledge. That requirement is what makes nearly every commercial function a variation of what happens on the outside of the door. Some functions add a separate deadbolt, but the egress side stays free so the opening always meets life-safety code.

The function codes you will actually order

These are the functions that cover the vast majority of commercial openings, with the door types they suit and the ANSI F-number for cylindrical and mortise versions.

The single most common error is ordering Office when the spec needs Storeroom. Office function lets a user leave the outside unlocked by pressing a button, while Storeroom never unlocks from a button, so the door stays secure and only a key gets in. Secured rooms such as IT, mechanical, and supply are almost always Storeroom. A unit like the Schlage L9480 storeroom mortise lock with deadbolt is a typical spec for those doors. For the mortise-versus-cylindrical decision that sits above the function choice, read mortise vs cylindrical locks, and for the deeper mortise function set, see the mortise locks guide.

Classroom vs Classroom Security: the lockdown question

Standard Classroom function locks and unlocks the outside lever with a key inserted from the corridor. The flaw is obvious in an emergency: during a lockdown a teacher would have to step into the hallway to lock the door. Classroom Security (also called Intruder or Classroom Holdback) adds a second cylinder or an inside key or thumbturn so the outside can be locked from inside the room without opening the door. Most modern K-12 specs now require Classroom Security, so confirm the function name on the spec, because the catalog numbers differ by brand even though both are loosely called classroom.

See how to choose a heavy-duty classroom lever lock and the commercial door hardware for K-12 schools guide for the full classroom-door spec. The same Classroom Security function drives lockdown planning in house of worship security hardware.

How brand catalog numbers map to functions

The ANSI F-number is the Rosetta Stone. Every major brand publishes its functions against the ANSI list, so you can substitute across brands by matching F-numbers rather than marketing names.

These are representative, not exhaustive, so always confirm the exact suffix (lever style, cylinder, finish) on the manufacturer current price book. Browse the function-coded product lines on our cylindrical lever locks and mortise locks category pages, or by brand on Schlage commercial, Sargent, and Corbin Russwin.

Functions that include a deadbolt

Some openings need a latch and a deadbolt in one chassis, which is the role of the entrance and apartment functions (the F13 and F14 mortise functions). Standalone auxiliary deadbolts are a separate order under A156.36. If the opening needs a deadbolt plus a latch in one unit, specify a mortise entrance or apartment function rather than adding a surface deadbolt. For standalone bolts, see how to choose the best commercial deadbolts.

Common function-spec mistakes

1. Office where Storeroom belongs. Secured rooms get left unlocked by the pushbutton. Use Storeroom for IT, mechanical, and supply rooms.
2. Standard Classroom in a lockdown jurisdiction. Specify Classroom Security so the door locks from inside the room.
3. Privacy on a door that needs a staff key override. Hospitals and senior care often need Privacy with an outside emergency key, not just a coin-slot tool.
4. Passage on a fire or egress door that needs positive latching. Passage latches still latch, but confirm the fire rating and never downgrade a fire door to a non-latching function.
5. Mismatched function across a substitution. When swapping brands, match the ANSI F-number, not the marketing name.

Function, grade, and lever design work together

A function code tells you how a lock behaves, but two more attributes decide whether it survives the opening it is installed on. The first is ANSI/BHMA grade. Grade 1 is the commercial heavy-duty tier and is the right default for any door with steady public traffic, while Grade 2 suits lighter interior openings. Specifying the function without the grade is how a correctly chosen Storeroom or Classroom lock still fails early, because the cycle count and strength rating were never matched to the traffic.

The second is lever design. On a locked function such as Storeroom or Classroom, the outside lever is rigid, and a forced push on that lever is a common failure point. A clutch or free-spinning lever solves this: when the lock is secured, the outside lever rotates freely or disengages instead of transmitting force into the internal retractor, which protects the latch train from vandalism and from everyday abuse. When you compare a Schlage ND, a Sargent 8200, or a Corbin Russwin CL lever in the same function, the clutch mechanism and the Grade 1 cycle rating are often what separate them on a real bid, not the function letter itself.

FAQ

What is the difference between Office and Entrance function?

Office function uses a key or inside pushbutton and is designed for a single private room. Entrance and Apartment function (F13/F14) adds a deadlocking latch and a thumbturn for suite or apartment doors, and is built for higher security at a unit door.

Is Storeroom function ADA compliant?

Yes. Storeroom keeps the outside lever rigid but the inside lever is always free, so egress meets ADA and life-safety code. The lever itself must still meet ADA shape and operating-force rules. See ADA compliance for commercial door hardware.

Can I change a lock function in the field?

Sometimes. Mortise locks often allow function changes by repositioning internal parts or swapping a cylinder or thumbturn, while cylindrical locks usually do not. Plan the function at order time rather than relying on field conversion.

What ANSI standard defines function codes?

A156.2 defines cylindrical (bored) lock functions and A156.13 defines mortise lock functions. Both list standardized F-numbers. See the BHMA A156 series cheat sheet.

How do I substitute one brand for another safely?

Match the ANSI F-number first, then confirm the lever style, cylinder type, and finish suffix on the current price book. The F-number guarantees the behavior is identical even when the catalog name differs.

Next step

Choose the function before you choose the brand, because it dictates which catalog number you order. Start from the cylindrical lever locks or mortise locks category, confirm the ANSI F-number against your spec, and pick the finish. Our commercial desk cross-references function codes across Schlage, Sargent, Corbin Russwin, and Yale so a brand substitution keeps the exact behavior the spec called for.