This really does attack essence. Because the build-on-package phenomenon does not today affect the average MIS programmer, it is not yet very visible to the software engineering discipline. Nevertheless, it will grow rapidly, because it does attack the essence of fashioning conceptual constructs. The shrink-wrapped package provides a big module of function, with an elaborate but proper interface, and its internal conceptual structure does not have to be designed at all. High-function software products such as Excel or 4th Dimension are big modules indeed, but they serve as known, documented, tested modules with which to build customized systems. Next-level application builders get richness of function, a shorter development time, a tested component, better documentation, and radically lower cost. The difficulty, of course, is that the shrink-wrapped software package is designed as a stand-alone entity whose functions and interfaces metaprogrammers cannot change. Moreover, and more seriously, shrink-wrapped package builders seemingly have little incentive to make their products suitable as modules in a larger system. I