reg

code, constitution, decalogue, directory

act, law, ordinance, statute

behest, charge, command, commandment, decree, dictate, direction, directive, edict, fiat, instruction, order

axiom, fundamental, maxim, precept

moral, principle, value

ban, interdiction, prohibition, proscription, restriction

convention, custom, habit, manners, mores, practice (also practise), tradition, way

blueprint, canon, formula, guide, guideline, standard