(e) That the Commission, with the approval of the President, has decided that such an examination should be held to test fitness for any particular place requiring technical, professional, or scientific knowledge, special skill, or peculiar ability, to test fitness for which place a competitive examination can not, in the opinion of the Commission, be properly provided.

  (f) That a person who has been appointed from the copyist
  register wishes to take the clerk examination for promotion to a place
  the salary of which is not less than $1,000 per annum.

  (g) To test the fitness of a person for a place to which his
  transfer has been requested.

  (h) When the exigencies of the service require such examination
  for promotion as provided by clause 6 of this rule.

  3.  All applications for examination must be made in form and manner
  prescribed by the Commission.

4.  No person serving in the Army or Navy shall be examined for admission to the classified service until the written consent of the head of the Department under which he is enlisted shall have been communicated to the Commission.

  No person who is an applicant for examination or who is an eligible
  in one branch of the classified service shall at the same time be an
  applicant for examination in any other branch of said service.

5.  The Commission may refuse to examine an applicant who would be physically unable to perform the duties of the place to which he desires appointment.  The reason for any such action must be entered on the minutes of the Commission.

6.  For the purpose of establishing in the classified civil service the principle of compulsory competitive examination for promotion, there shall be, so far as practicable and useful, compulsory competitive examinations of a suitable character to test fitness for promotion; but persons in the classified service who were honorably discharged from the military or naval service of the United States, and the widows and orphans of deceased soldiers and sailors, shall be exempt from such examinations.

The Commission may make regulations, applying them to any part of the classified service, under which regulations all examinations for promotion therein shall be conducted and all promotions be made; but until regulations in accordance herewith have been applied to any part of the classified service promotions therein shall be made in the manner provided by the rules applicable thereto.  And in any part of the classified service in which promotions are made under examination as herein provided the Commission may in special cases, if the exigencies of the service require such action, provide noncompetitive examinations for promotion.