A policy may do any one or more of the following--
(a) apply generally or be limited in its application by reference to specified exceptions or factors,
(b) apply differently according to different factors of a specified kind,
(c) authorise any matter or thing to be determined according to the discretion of the EPA or any other person,
(d) refer to or incorporate, with or without modification, a standard or other document prepared or published by a body specified in the policy, as in force at a particular time or from time to time.