1. 指导方针；指导原则；准则
If an organization issues guidelines on something, it issues official advice about how to do it.

2. 参考
A guideline is something that can be used to help you plan your actions or to form an opinion about something.

1. a rule or principle that provides guidance to appropriate behavior

Synonym: guidepostrule of thumb

2. a detailed plan or explanation to guide you in setting standards or determining a course of action

e.g. the president said he had a road map for normalizing relations with Vietnam

Synonym: road map

3. a light line that is used in lettering to help align the letters