When set up an individual TWT agreement, the flow id will be assigned by AP after a successful agreement setup. flow_id could be specified to a value in the range of [0, 7], but it might be changed by AP in the response. When change TWT parameters of the existing TWT agreement, flow_id should be an existing one. The value range is [0, 7].
Nominal Minimum Wake Duration, indicates the minimum amount of time, in unit of 256 us, that the individual TWT requesting STA expects that it needs to be awake. The value range is [1, 255].