1. An apparatus for generating a model reference testcase for a target system, the apparatus comprising: a computer system having an electronic memory storage device, a knowledge base stored on said electronic memory storage device, said knowledge base having a set of functional description data relating to the target system; a user interface program executable by said computer system, said user interface program for inputting a high-level testcase request and for converting said testcase request into an output file; and a testcase generation program executable by said computer system, said testcase generation program accepting as an input argument said output file of said user interface program, said testcase generation program having access to said knowledge base for processing said output file into an executable testcase, said testcase generation program having a plurality of generation modules arranged in an open chain configuration.