Each quark or antiquark obeys the Gell-Mann-Nishijima formula individually, so any additive assembly of them will as well.

Mesons are made of a valence quark-antiquark pair (thus have a baryon number of 0), while baryons are made of three quarks (thus have a baryon number of 1). This article discusses the quark model for the up, down, and strange flavors of quark (which form an approximate flavor SU(3) symmetry). There are generalizations