addition the number of the medium pairs is counted in the list n 1 assume here the number is n 1 step 1004 subsequently in the similar fashion the other one for example the medium y of the paired media x y is moved to a different area thereafter there is selected a pair of media stored in the same area so as to be recorded in the list n 2 in addition the number of the medium pairs is counted in the list n 2 assume here the number is n 2 step 1005 the system determines the maximum value among the numbers m n 1 and n 2 representing the medium pairs in the three lists m n 1 and n 2 respectively if the maximum value is m n 1 or n 2 control is transferred to step 1006 1007 or 1008 respectively step 1007 of the pair of media x y the medium x is rearranged in another area and then the medium pair x y is deleted from the list m step 1008 of the pair of media x y the medium y is rearranged in another area and then the medium pair x y is deleted from the list m step 1009 a check completion mark is assigned to the medium pair x y in the list l step 1010 the system judges to determine whether or not there exists any medium pair to be checked in the list l if there exists a remaining pair control is passed to step 1002 otherwise the processing is terminated next description will be given of an embodiment in which the selection of a recording playback apparatus is achieved depending on two criteria as follows 1.