Section 193.2009 - Rules of regulatory construction(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.