Roof cert question

I was curious on the roof cert form it asks, if updated was it a partial or full replacement. For partial are they talking about just a section of the roof being repaired, or do they consider a re-roof a partial repair. Just want to make sure I am reading and comprehending this correctly. And when they talk about secondary roof, would a flat roof over a pool deck area be considered secondary, just curious what qualifies for a secondary roof. I searched online but I am still a little confused. Thanks in advance

A full re-roof is a full replacement update of each roof covering type. A partial update is just what is says, if the front half of the shingle roof was replaced, then it is a 50% partial update. If the rear porch roof is not enclosed and not structurally attached, it does not go on the form.

Thank you