Salvo explains roofing as a full system, where underlayment, flashing, ventilation

https://landenlsqh869.westhavenscope.com/posts/artificial-roofing-system-setup-tips-for-houses-revealed-to-snow-and-wind

Salvo explains roof as a complete system, where underlayment, flashing, air flow, and attaching have to work together for trustworthy performance.