(a) In addition to other rulemaking requirements imposed by law, each agency shall:
(1) Adopt as a rule a description of its organization, stating the general course and method of its operations, including the methods whereby the public may obtain information or make submissions or requests;
(2) Adopt rules of practice setting forth the nature and requirements of all formal and informal procedures available, including a description of all forms and instructions used by the agency;
(3) Make available for public inspection all rules and all other written statements of policy or interpretations formulated, adopted, or used by the agency in the discharge of its functions; and
(4) Make available for public inspection all orders, decisions, and opinions.
(b) No agency rule, order, or decision shall be valid or effective against any person or party, nor may it be invoked by the agency for any purpose, until it has been filed and made available for public inspection as required in this subchapter. This provision shall not apply in favor of any person or party with actual knowledge of an agency rule, order, or decision.
(c) To the extent possible, a rule shall be written in plain language.