u/Southern_Lifeguard37

I'm reading an inspection report and there's an inspection item that says "The purlin system that supports the middle span of the roof frame is missing a proper strut system. This can cause sagging in the roof frame over time and should be further investigated and repaired by a qualified general contractor to ensure reliable performance from the roof frame system." Can someone explain what is missing here? I've tried watching videos to figure out where/what the missing pieces are, but it's not obvious to me. I'm also trying to gauge if this is a repair that's 1-2 days of work, or is it something like "rip the whole roof off and start over". Any insight is appreciated!