Wire-format Alerting for Risk Notification

This document describes WARN, a transport-agnostic compact binary wire protocol used for emergency alerts under constrained hardware and lossy networks. It is designed to reach farther and quicker than OASIS CAP, which tries to deliver full human-readable information at the cost of complexity. It primarily uses fixed fields, with support for TLVs when more expressiveness is required. It also has a mandatory signature to prevent fake alerts propagating through a mesh.