  Noticing renewed or increasing interest in the possibility to describe
semirelativistic bound states (of either spin-zero constituents or, upon
confining oneself to spin-averaged features, constituents with nonzero spin) by
means of the spinless Salpeter equation generalizing the Schr\"odinger equation
towards incorporation of effects caused by relativistic kinematics, we revisit
this problem for interactions between bound-state constituents of Yukawa shape,
by recalling and applying several well-known tools enabling to constrain the
resulting spectra.
