Guideline

(noun) a light line that is used in lettering to help align the letters. Synonyms: guideline.

(noun) a detailed plan or explanation to guide you in setting standards or determining a course of action. Synonyms: road map, guideline. Example: "The president said he had a road map for normalizing relations with vietnam."

(noun) a rule or principle that provides guidance to appropriate behavior. Synonyms: guidepost, guideline, rule of thumb.