You posted this in Fire Codes, but is this question related to accessibility?
"Common use" is used throughout the code with some varied meaning, but its primary use is in the accessibility provisions, such as
IBC Section 1104.3.1. In the context of accessibility and the section below, "common use" is a defined term, which follows the example code section that I think you may be working with.
1104.3.1 Employee Work Areas
Common use circulation paths within employee work areas shall be accessible routes.
Exceptions:
- Common use circulation paths, located within employee work areas that are less than 1,000 square feet (93 m2) in size and defined by permanently installed partitions, counters, casework or furnishings, shall not be required to be accessible routes.
- Common use circulation paths, located within employee work areas, that are an integral component of equipment, shall not be required to be accessible routes.
- Common use circulation paths, located within exterior employee work areas that are fully exposed to the weather, shall not be required to be accessible routes.
[BE] COMMON USE. Interior or exterior circulation paths, rooms, spaces or elements that are not for public use and are made available for the shared use of two or more people.