(a) As used in this part:

(1) Includes means including but not limited to;

(2) May means is permitted to or is authorized to;

(3) May not means is not permitted to or is not authorized to; and

(4) Shall or must is used in the mandatory and imperative sense.

(b) In this part:

(1) Words importing the singular include the plural; and

(2) Words importing the plural include the singular.