Complex sentence: The first appearance of "octothorp" in a US patent is in a 1973 filing, which also refers to the six-pointed asterisk (✻) used on telephone buttons as a "sextile".
Split into simpler sentences: The first appearance of "octothorp" in a US patent is in a 1973 filing. This patent also refers to the six-pointed asterisk (✻) used on telephone buttons as a "sextile".