It is asserted that the current signalling design of output pictures and their association to input pictures in NNPFA SEI message has a bug / an overlook. In the signalling of the output pictures association with input pictures, there are constraints specified in NNPFC SEI message to ensure that at the NNPF shall produce output picture(s). However, when the signalling of output pictures association with input pictures is updated in the NNPFA SEI message, it is possible that the activated NNPFA does not output any picture after the signalling of the output picture flags in the NNPFA SEI message.