What format is the deconstructed payload from the Serial Library?
The raw bytes are packaged into a frame object that your application can work with, depending on which programming language version of the Serial Library you are using. In Java, for example, the payloads are returned as instances of pre-defined classes for the message being received. In terms of the format of payload parameters, you'll have options to retrieve raw bytes or additional objects which can further be broken down (i.e. an IEEEAddress object, for a device network MAC address).