one, and one only, and shall notify the person whose name has been selected that he has been designated for appointment:  Provided That, for the purpose of maintaining the apportionment of appointments referred to in clause 2 of this rule, the Commission may authorize the appointing officer to select more than one of the three names certified.

  When certification is made from a supplementary or a special register,
  and there are more vacancies than one to be filled, the appointing
  officer may select from the three names certified more than one.

4.  The Commission may certify from the clerk register for appointment to a place the salary of which is less than $1,000 per annum any eligible on said register who has given written notice that he will accept such a place.

5.  When a person designated for appointment shall have reported in person to the appointing officer, he shall be appointed for a probational period of six months, at the end of which period, if his conduct and capacity be satisfactory to the appointing officer, he shall receive absolute appointment; but if his conduct and capacity be not satisfactory to said officer he shall be notified that he will not receive absolute appointment, and this notification shall discharge him from the service.  The appointing officer shall require the heads of bureaus or divisions under whom probationers are serving to keep a record and to make report of the punctuality, industry, habits, ability, and aptitude of each probationer.

6.  All persons appointed to or promoted in the classified departmental service shall be assigned to the duties of the class or place to which they have been appointed or promoted, unless the interests of the service require their assignment to other duties; and when such assignment is made the fact shall be reported to the head of the Department.

  DEPARTMENTAL RULE VIII.

  1.  Transfers will be made as follows: 

  (a) From one Department to another, upon requisition by the head
  of the Department to which the transfer is to be made.

(b) From a bureau of the Treasury Department in which business relating to the customs is transacted to a classified customs district, and from such a district to such a bureau of the Treasury Department, upon requisition by the Secretary of the Treasury.

  (c) From the Post-Office Department to a classified post-office,
  and from such an office to the Post-Office Department, upon requisition
  by the Postmaster-General.