Logically, the TV is on top and ends the "up" chain-path, translating the electrical info into an image and sound. From the same logical point of view the info stream, wherever it originates, may need processing such as decrypting (decoding, descrambling) or adding captioning/subtitles. In this case the info stream is sent logically "down" to dedicated function devices. From the last processing device the info stream is sent logically "up" to the TV, through all the chain-path. Another case is when the info stream is sent "down" and not expected to be sent back "up", for example when sent to a recorder.