Whether the frame acknowledges the last confirmed one.
Whether the frame takes part in adaptive data rate.
Whether the frame asks to be acknowledged.
OptionaldevThe device address, or null for a join frame.
OptionalfcntThe low 16 bits of the frame counter, or null for a join frame.
How many bytes of frame options the header carries.
Whether the network has more downlink data waiting.
OptionalfportThe port, or null for a join frame or one carrying only options.
Whether this is a data frame rather than part of a join exchange.
What kind of message the frame is.
The length of the still-encrypted payload.
What a frame says about itself before any key is involved.
Nothing here is authenticated, since checking the MIC needs the session key. Treat it as a routing hint until
decodehas verified the frame.