SF-50 says “Schedule B” in Box “5-D Legal Authority”

My SF-50 says “Schedule B” in Box “5-D Legal Authority” and I'm not sure what that means. I was hired about 10 months ago through a regular application on USAjobs. Does anyone know more about Schedule B and what it means? I'm trying to figure out if I'm going to be reclassified as easy to fire, just like Schedule F employees are currently going through.