Primary broadly means it comes straight from statute or is not reliant on the exercise of any other duty, power, event or occurrence of an event in order to exercise it. Secondary means that it does not come straight from statute or is reliant on the exercise of another duty, power, event or occurrence of an event in order to exercise it. 

The terminology used is for guidance only and does not reduce or in any way negate the need to comply with or to use any particular power or duty. It's important to bear in mind that the terminology used is for guidance only and should be used in consultation with legal services, ideally. The terms are not supposed to be definitive but they might be useful in identifying where legal assurance should be sought.