  We classify the possible shapes of cosmic string cusps and how they transform
under Lorentz boosts. A generic cusp can be brought into a form in which the
motion of the cusp tip lies in the plane of the cusp. The cusp whose motion is
perpendicular to this plane, considered by some authors, is a special case and
not the generic situation.
  We redo the calculation of the energy in the region where the string overlaps
itself near a cusp, which is the maximum energy that can be released in
radiation. We take into account the motion of a generic cusp and the resulting
Lorentz contraction of the string core. The result is that the energy scales as
$\sqrt {rL}$ instead of the usual value of $r^{1/3} L^{2/3}$, where $r$ is the
string radius and $L$ and is the typical length scale of the string. Since $r
<< L $ for cosmological strings, the radiation is strongly suppressed and could
not be observed.
