Update: Specification FSS-000E (Payload), add "signature" Object section.

Update: Specification FSS-000E (Payload), add "signature" Object section.

Provide an optional "signature" Object and associated Content rules to the specification.
This better separates defining how the "header" and "payload" can be signed or have checksums applied.
The actual rules are left rather vague and flexible for implementation specific decisions.

A suggested strategy for using the "signature" is provided within the example.