  We examine possible assignments for known mesons to the predicted
ground-state q bar q multiplets in the U~(12)_SF-classification scheme of
hadrons, based on their observed properties. The masses of missing members of
the ground-state multiplets are estimated, using a phenomenological mixing
scheme for the normal- and extra-spin wave functions specific to this
classification scheme. We also examine experimental candidates for the excited
1P, 1D and 2S multiplets in a framework of the U~(12)_SF X
O(3,1)_L-classification scheme, based on the analysis of the ground-state
masses. Then we see that the two exotic mesons pi_1(1400) and pi_1(1600) with
J^PC=1^-+ have suitable masses to be assigned to the P-wave excitation and also
there are a number of observed mesonic states which could be classified in
terms of the U~(12)_SF X O(3,1)_L scheme.
