Simple derivation from postulates of generalized vacuum Maxwell equations

The two postulates of special relativity plus the postulates of conserved charges, both electric and magnetic, and a resulting linear system are sufficient for the derivation of the generalized vacuum Maxwell equations with both charges. The derivative admits another set of Maxwell equations for charges that are the opposite-parity partners of the usual electric and magnetic charges. These new charges and their photons are parts of the parallel universe of dark matter.