Abstract
This paper presents a modeling tool, so-called X-ADD (X-window application Analysis & Design Diagram), which is useful for the understanding of existing X-window application program and the development of new X-window application software. This X-ADD tool is available for the X-window applications maintenance activities such as program understanding, and program analysis by the concept of reverse engineering. In addition, it supports the analysis and design for the new X-window application system development. Therefore, by the use of this tool, the visibility of the existing X-window application programs can be enhanced and modeling for the design of new X-window application systems can be easily made.