Supply
The inventory, storage, and resupply layer that keeps the system functional.
Supply & Sustainment is the part of the system that keeps everything else working over time.
Field kits and modules are what you use. Sustainment is how you refill them, replace expired items, track inventory, and keep the system alive.
This includes bulk supplies, storage, expiration tracking, PPE, replacement parts, medications, labels, checklists, and resupply planning.