A more thorough explanation:

A parliamentary manual is a book that contains rules and guidelines for conducting meetings and making decisions in a parliamentary setting. It is usually published commercially and can be adopted by organizations as their parliamentary authority.

For example, Robert's Rules of Order Newly Revised is a popular parliamentary manual used by nonlegislative bodies such as clubs, associations, and corporations. Mason's Manual of Legislative Procedure, on the other hand, is a parliamentary manual used by state legislatures.

These manuals provide guidance on how to conduct meetings, make motions, vote, and handle other parliamentary procedures. They help ensure that meetings are conducted in an orderly and fair manner, and that decisions are made democratically.