  We find the structure of generators of norm continuous quantum Markov
semigroups on B(h) that are symmetric with respect to the scalar product
tr(\rho^{1/2}x\rho^{1/2}y) induced by a faithful normal invariant state
invariant state \rho and satisfy two quantum generalisations of the classical
detailed balance condition related with this non-commutative notion of
symmetry: the so-called standard detailed balance condition and the standard
detailed balance condition with an antiunitary time reversal.
