  We elaborate the frame dependence of the angular conditions for spin-1 form
factors. An extra angular condition is found in addition to the usual angular
condition relating the four helicity amplitudes. Investigating the
frame-dependence of the angular conditions, we find that the extra angular
condition is in general as complicated as the usual one, although it becomes
very simple in the $q^+ = 0$ frame involving only two helicity amplitudes. It
is confirmed that the angular conditions are identical in frames that are
connected by kinematical transformations. The high $Q^2$ behaviors of the
physical form factors and the limiting behaviors in special reference frames
are also discussed.
