The term "administrative disposition" in this Act denotes a unilateral administrative act with direct external effects, rendered by an administrative authority in making a decision or taking other actions within its public authority, in respect of a specific matter in the area of public law. Where the persons subject to a decision or actions referred to in the preceding paragraph, although unspecified, are definable in light of their general characteristics, such a decision or action constitutes a general disposition, to which the provisions herein set forth with respect to administrative dispositions shall apply.