Composite Young diagrams, supercharacters of U(M/N) and modification rules

The supercharacter of U(M/N) associated with an arbitrary composite Young diagram is defined. The distinction is made between standard and non-standard supercharacters. A modification rule is presented which may be used to express any non-standard supercharacter in terms of standard supercharacters. In the case N=0 the rule reduces to the rule already known to be appropriate to U(M).