  In this paper, we present some geometric characterizations of the Moufang
quadrangles of mixed type, i.e., the Moufang quadrangles all the points and
lines of which are regular. Roughly, we classify generalized quadrangles with
enough (to be made precise) regular points and lines with the property that the
dual net associated to the regular points satisfy the Axiom of Veblen-Young, or
a very weak version of the Axiom of Desargues. As an application we obtain a
geometric characterization and axiomatization of the generalized inversive
planes arising from the Suzuki-Tits ovoids related to a polarity in a mixed
quadrangle. In the perfect case this gives rise to a characterization with one
axiom less than in an already known result by the second author.
