This refers to the specific features available in different door locks. A passage lockset is one with free access in both directions (non-locking). A privacy lock is commonly found on bathrooms, bedrooms and dressing rooms. An entry lockset is the familiar type with a button on the inside and a keyhole on the outside. Storeroom locks are always free from the inside, but are always locked from the outside. (Building codes typically specify storeroom locks on rooms used to store toxic chemicals.) There are dozens of varieties that professional locksmiths can recommend and supply. Whatever your security needs, there is probably a lock function designed to address it!