(_a_) From one office of a classified district to another office in
the same district, subject to the provisions of Customs Rule V.
(_b_) From one classified district to another, upon requisition by
the Secretary of the Treasury.
(_c_) From any bureau of the Treasury Department in which business
relating to customs is transacted to any classified customs district,
and from any such district to any such bureau, upon requisition by the
Secretary of the Treasury.
2. No person may be transferred as herein authorized until the board of
examiners, acting under (_a_) of clause I, or until the Commission,
acting under (_b_) or (_c_) of clause i of this rule, shall
have certified to the officer making the transfer requisition that the
person whom it is proposed to transfer has passed an examination to test
fitness for the place to which he is to be transferred, and that such
person has been at least six months preceding the date of the
certificate in the classified service of the Department or customs
district from which the transfer is to be made.