referred by media processing industries is an example of that. Open source software development, which has already reached the Productization phase, is now making its presence felt in the Service and Variation phase. The industry evolution may also stop in the Productization phase if the compet- ing technologies and interfaces have insufficient critical mass to drive the positive cycle. There has been, for instance, a wide variety of fieldbuses used by various vertical industries to connect sensors and actuators with control units in real-time distributed control systems. Some of them have provided inexpensive solutions for industries with easier requirements, some of them have priced themselves out or are much less applicable to real needs. As a result, none of these fieldbus systems has been accepted widely as a dominant design. A long competition among Unix plat- forms is another example of the evolution stuck in the Productization phase. Importance of Interfaces The effort needed to implement a software system can be minimized by using existing software implemented by others. The use of such existing software com- monly assumes a modularized system design, wherein the interacting modules are integrated through interfaces. These existing subsystems act as the containers for knowledge transfer from external organizations to the software system developer. Thus, the availability of system components with easy-to-use interfaces reduces greatly the knowledge required by the developers. If the interface is standardized, the software developer does not have to understand the details of the system used, whereas employing nonstandard interfaces with variations often demands a profound knowledge of the system. The requirement to master a large number of proprietary technologies and to have the necessary industry process knowledge can be too much for most of the software development organizations. This may limit the critical mass of the organization needed for reaching the next phase in the vertical industry evolution. F