This Act imposes an estate duty upon the estates of deceased persons. For the purposes of this Act, the estate of any person shall consist of: (a) all property of that person as at the date of his or her death and which was acquired by that person on or after a specified date; (b) all property which, according to provisions of this Act, is deemed to be property of that person at the date of his or her death; and (c) all property of that person as at the date of his or her death which is and whic