PLC Memory Sizing

I am working on sizing a compactlogix plc based on user memory. Allen Bradley uses the following protocol below. Can someone explain what is defined as a controller task? Is this essentially every instruction task I will be using in the logic is considered as 1 controller task? ie an XIC is considered 1 task?

Estimate Controller Memory Use

The following equations provide an estimate of the memory needed for a controller.

Controller Tasks _____ * 4000 = _____ bytes (minimum 1 task)

Digital I/O points _____ * 400 = _____ bytes

Analog I/O points _____ * 2600 = _____ bytes

Communication modules¬ _____ * 2000 = _____ bytes

Motion axes _____ * 8000 = _____ bytes

FactoryTalk alarm instruction _____ * 1000 = _____ bytes(per alarm)

FactoryTalk subscriber _____ * 10000 = _____ bytes per subscriber)

Controller tasks are execution scheduling structures.
A simple program only has one controller task executing continuously. You can create other tasks with higher priority that execute on timed schedules or triggered by events if required.