Which kind of device it is for, as 16 bytes.
The SHA-256 of the payload, which every other guarantee rests on.
When this release stops being offered, in seconds since the Unix epoch,
or 0 to never expire.
How the payload is encoded, currently only UPDATE_FORMAT_RAW.
Rises with every release, which is what stops an older image being replayed at a device.
The payload length in bytes, known before a single byte is accepted.
Which slot the payload belongs in.
Which iteration of the manifest format this is.
Who built the image, as 16 bytes.
What a release says about itself, and what a device checks it against.