This lecture is devoted to the Drexel University Shell Model (DUSM) co
de; this is a new shell-model code based on a separation of the variou
s subspaces in which the single particle wavefunctions are defined. Th
is is achieved via extensive use of permutation group concepts and a r
edefinition of the, Coeficients of Fractional Parentage (CFP) to inclu
de permutation labels. This leads to a modern and efficient approach t
o nuclear shell-model.