f9 sec 14 which is sick. 14.d.4. Return to work.
“The company retains the right to request that a pilot who is absent due to illness or injury furnish the company with a physician’s certificate, describing the medical condition that resulted in the pilots absence. This request shall only be made when there is a reasonable basis to question the pilots absence.”
That turned into a practice argument where it’s never really questioned outside of a few different circumstances. Think patterns (every other Tues, every holiday, ect…)

f9 sec 13 which is leave of absence. Not to be confused with sec 14 sick has similar language but starts to force management to pay for medical expenses and time off if they want to question a physician note.
The intent is to prevent another German wings scenario when a pilots is returning from an issue where they have been out of communication with the company for a longer period of time. I believe most alpa carriers have similar language because it’s driven by insurance companies.