  Particles of spin 1/2 and 1 in external Abelian monopole field are
considered. P-inversion like operators N-s commuting with the respective
Hamiltonians are constructed: N(bisp.) is diagonalized onto the relevant wave
functions, whereas N(vect.) does not. Such a paradox is rationalized through
noting that both these operators are not self-conjugate. It is shown that any
N-parity selection rules cannot be produced. Non-Abelian problems for doublets
of spin 1/2 and 1 particles are briefly discussed; the statement is given of
that corresponding discrete operators are self-conjugate and selection rules
are available.
