At Republic, any sick call is an "occurence". Get too many per calendar year, and you can be terminated. Other "occurence" worthy items are late show, UNA's when on RSV and so forth. A "No-call/No-show" is worth 4.
A fatigue call is not supposed to be an occurence, but you WILL get a phone call from the Chief Pilot who will tell you that you MUST take the flight. They make every attempt to bully you to stay in the seat and complete the flight. The scheduler will also "conveniently" code the call as UNA and that stays as an occurence until you convince the CP or DO to change it to a fatigue call.
The IBT (union) has said they are powerless to do anything to stop the occurence policy. (this is after losing an arbitration on a similar issue)
Calling in sick at Republic results in the Crew Scheduler telling you that you are going to need a Dr.'s note. W*T*F?