OPM will determine the standards to be used in issuing Letters of Authority, which shall include the following:
(a) The positions to be filled must be related to emergency situations for which the usual recruiting methods are inadequate.
(b) The positions must be a part of a specific program immediately essential to the national interest.
(c) The positions must be essential to the functioning of the program.
(d) There must be substantial basis for the belief that reemployment rights will be a significant and reasonable aid in meeting the emergency situation.