Flavor changing neutral currents and multileptons in e+e- and γsub(μ)N, anti γsub(μ)N

New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e+e-, γsub(μ)N, anti γsub(μ)N. It is observed that (i) e+e- is a favored place to search for their effects through inclusive ratios sigma(e+e-+x):sigma(μ+μ-+x):sigma(e+-μ-++x) and same sign leptons e+-e+-+x, μ+-μ+-+x, e+-μ+-+x. Above a new flavor threshold four charged lepton final states may become important. (ii) Trilepton final states in γsub(μ)N, anti γsub(μ)N are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes anti γsub(μ)N→e+e-+... and (for charm-changing neutral currents) anti γsub(μ)N→e++... . (Auth.)