GUIDELINE

:''"Guideline" is the NATO reporting name for the Soviet SA-2 surface-to-air missile.''
A 'guideline' is any document that aims to streamline particular processes according to a set routine. By definition, following a guideline is never mandatory (protocol would be a better term for a mandatory procedure). Guidelines are an essential part of the larger process of governance.
Guidelines may be issued by and used by any organization (governmental or private) to make the actions of its employees or divisions more predictable, and presumably of higher quality.
Examples or guidelines are:

★ Federal Sentencing Guidelines

★ Medical guidelines

★ Human interface guidelines