Message submission and sending

flowchart TD
Compose["Submit text"] --> Validate{"}
Validate -- No--> Reject["Reject"]
Validate -- Yes--> Queue["Message identity + Queued"]
Queue --> Encode["Protocol encoding"]
Encode --> Radio["radio queue"]
Radio --> Sent["Sent"]
Sent --> Ack{"ACK?"}
Ack -- Yes--> Delivered["Delivered"]
Ack -- Timeout--> Failed["Failed"]