We provide this module to users as template for potential addition of behavior etc. As is, the module simulates multiple classes of passive tracers with constant settling velocity gen_wsett (`gen_wsett` <0 =>swimming velocity), with no body forces and zero fluxes at surface and bottom. The number of generic tracers is specified as `ntracer_gen`. I.C. flag is `flag_ic(3)`, and nudging flag is `inu_tr(3)` in `param.nml`. The output flags are `iof_gen(1:ntracer_gen)`.