If the two hadrons A and B are precisely the same, the final state
has well defined charge conjugation which the above arguments
require to be C = -1. This immediately implies 
and, consequently, the vanishing of the form factors
at all 
for all the self-conjugate hadrons 
, i. e.,
those having all internal charges equal to zero. This is the case for
the truly neutral mesons 
, but not for the electrically neutral mesons 
or baryons 
having other internal charges and
an electromagnetically active substructure.
-data for the elastic form factors of a non-neutral
hadron A, 
, cover the time-like region, 
, and
complement the values of the corresponding spacelike region,
.
These are deducible from A-elastic scattering
experiments on electrons, 
, (as well as on other e.m.
fields) and contain the hadronic current matrix element 
with 
.
