  We review the construction and theoretical implications of the USp(2k) matrix
model in zero dimension introduced in ref. \cite{IT1,IT2}. It is argued that
the model provides a constructive approach to Type I superstrings and is at the
same time dynamical theory of spacetime points. Three subjects are discussed :
semiclassical pictures and series of degenerate perturbative vacua associated
with the worldvolume representation of the model, the formation of extended
(D-)objects from the fermionic integrations via the (non-)abelian Berry phase,
and the Schwinger-Dyson/loop equations which exhibit the joining-splitting
interactions required. Lectures presented at the 13th Nishinomiya-Yukawa
Memorial Symposium ``Dynamics of Fields and Strings'' (November 12-13,1998) and
at the YITP workshop (November 16-18, 1998).
