Would like to see it here to be for sure but to me sounds like the triangle (a flag) is showing that a component is inop at time of installation. You will see these or similar alot of STC or engineering drawings for new installations as components will he installed wired up tested but then be INOP or unusable until final approval from authorities. Then revision will be made and inop flag removed.
Could be other reasons but that's the only one I can think of.