Manners are a first form of legal-law.
So this subject of science is near the science of legal-law. Manners can be divided into good manners and bad manners. But legal-law seems to be a coded system that is nearly all about bad things, bad manners or laws broken. And in a sense, it seems as though manners is a more generalized human conduct than is the legal-law. That is our actions and behaviour towards someone in respect to greeting is a form of manners, and if we assault them is another form of manner which carries over into legal-law.