During progressing schedule P6 uses Retained logic, progress override and actual dates options used. When each option should be used?

Retained Logic (RL): The retained logic schedule calculation setting holds schedule logic constant during calculation of in progress schedules.  The calculation adds activity remaining duration in the forward pass calculation for early dates and waits until activity predecessors are completed.

Progress Override (PO):  When the progress override schedule calcluation option setting is utilized, Oracle Primavera P6™ignores the predecessor activity relationships and calculates the activity completion date based on its own remaining duration.

Actual Dates (AD): When the actual dates schedule calcluation option setting is utilized, Oracle Primavera P6™sets the late finish date of the predecessor activity one day before the actual start of the out of sequence activity. This normally creates negative float to predecessor activities.