IOE/OE initial operating experience, kind of like mission seasoning. Usually your first 25 hours+- flown with a LCA/line check airman/SEFE

CSK consolidation of skills & knowledge, a defined timetable (usually 90d after your initial PC/proficiency checkride) that you have to log 100 hours or you get to reset with another sim check. You normally track this and notify training if you are not on track.