ground rule, reg, regulation, rule

code, constitution, decalogue, directoryact, law, ordinance, statutebehest, charge, command, commandment, decree, dictate, direction, directive, edict, fiat, instruction, orderaxiom, fundamental, maxim, preceptmoral, principle, valueban, interdiction, prohibition, proscription, restrictionconvention, custom, habit, manners, mores, practice(also practise), tradition, wayblueprint, canon, formula, guide, guideline, standard