Like notaries, witnesses aren't generally required in order for a contract to be legally enforceable. However, each state may require special kinds of contracts (e.g., real estate deals, wills, and marriage agreements) to be witnessed by a third party in order to be binding.
McDonald's, apparently, use red and yellow because red=fast and yellow=hunger (hence fast food!). Remember also that meaning is what we create. It does not exist in the color itself and individual meanings may or may not exist in different cultures and individuals.
G.fast is a new digital subscriber line (DSL) standard for local loops of under 500m, which targets performance of between 150Mbps and 1Gbps depending on distance from the distribution point, whether that be a fibre cabinet or a remote node.