  Linear combinations $D_K$ of the complete polarization-transfer observables,
Dij, in the (p,p') reaction at intermediate energies are demonstrated. A
comparison between systematized measured and calculated values of the
combinations $D_K$ for the $1^+$ (T = 0 and T = 1) levels in $^{12}$C, for the
$4^-$ (T = 0 and T = 1) states in $^{16}$O, and for the $6^-$ (T = 0 and T = 1)
levels in $^{28}$Si are reported. Particularities in angular distributions of
transverse- and longitudinal-spin-transfer probabilities, $D_K$, for the T = 0
and T = 1 unnatural-parity states in the indicated nuclei are discussed. The
spin-observable combinations Dls allowed to differentiate reliably the strength
of the isoscalar and isovector spin-orbit interactions. The comparison of
experimental $D_K$ and calculated $D_K$ with the use of zero-range treatment
(LEA code) and exact finite-range calculations (DWBA-91 program) made it
possible to identify the role of exchange contributions.
