21.—(1) The Reserve Defence Force shall be divided into the following classes—

(a) a class to be called the Reserve of Officers (First Line) which shall consist of such officers of the Reserve Defence Force as may from time to time stand assigned to that class under section 44,

(b) a class to be called the Reserve of Officers (An Fórsa Cosanta Aitiúil) which shall consist of such officers of the Reserve Defence Force as may from time to time stand assigned to that class under section 44,

(c) a class to be called the Reserve of Officers (An Slua Muirí) which shall consist of such officers of the Reserve Defence Force as may from time to time stand assigned to that class under section 44,

(d) a class to be called the Reserve of Men (First Line) which shall consist of—

(i) men (other than men who for the time being stand assigned to another class of reservists under subsection (2) of section 62) who, having enlisted under section 53, are transferred to the Reserve Defence Force in pursuance of section 70 and are for the time being reservists,

(ii) men (other than men who for the time being stand assigned to another class of reservists under subsection (2) of section 62) who are enlisted under section 55 for service in that class and are for the time being reservists, and

(iii) such reservists as may from time to time stand assigned to that class under section 62,

(e) a class to be called the Reserve of Men (An Fórsa Cosanta Aitiúil) which shall consist of—

(i) men (other than men who for the time being stand assigned to another class of reservists under subsection (2) of section 62) who are enlisted under section 55 for service in that class and are for the time being reservists, and

(ii) such reservists as may from time to time stand assigned to that class under section 62,

(f) a class to be called the Reserve of Men (An Slua Muirí) which shall consist of—

(i) men (other than men who for the time being stand assigned to another class of reservists under subsection (2) of section 62) who are enlisted under section 55 for service in that class and are for the time being reservists, and

(ii) such reservists as may from time to time stand assigned to that class under section 62,

(g) such other classes as may be constituted by the Minister under subsection (2) or (3) of this section.

(2) (a) The Minister may by regulations constitute such and so many classes of officers of the Reserve Defence Force as he thinks fit and assign to any class so constituted such title as he thinks fit.

(b) A class of the Reserve Defence Force constituted under this subsection shall consist of such officers of the Reserve Defence Force as may from time to time stand assigned to that class under section 44.

(3) (a) The Minister may by regulations constitute such and so many classes of reservists as he thinks fit and assign to any class so constituted such title as he thinks fit.

(b) A class of the Reserve Defence Force constituted under this subsection shall consist of—

(i) men (other than men who for the time being stand assigned to another class of reservists under subsection (2) of section 62) who are enlisted under section 55 for service in that class and are for the time being reservists, and

(ii) such reservists as may from time to time stand assigned to that class under section 62.

(4) If at any time there are no members of the Reserve Defence Force for the time being assigned to a particular class of the Reserve Defence Force, the Minister may by regulations abolish that class.

(5) The Minister may from time to time by regulations substitute for the existing title of a particular class of the Reserve Defence Force such other title as he thinks fit and specifies in the regulations.