I. Introduction
Extension development is made without fixing the existing source code of large-scale information and control systems, such as that for railway systems [1] and electronic power systems, in order to maintain the existing functions. As a result, their software structures become more and more complicated in longtime use. For example, some new data tables are added without changing the existing data tables even if they represent the same facilities defined by the existing ones. Thus, the source code for the data and data access are scattered throughout the program, and thus it is difficult to modify them. Therefore, a drop in the productivity becomes a problem. We have been developing legacy migration techniques to convert to a software structure with an improved level of productivity to try to solve this problem.