在软件开发过程中常用图作为描述工具。DFD就是面向(19)分析方法的描述工具。在一套分层DFD中，如果某一张图中有Ⅳ个加工(process)，则这张图允许有(20)张子图。在一张DFD图中，任意两个加工之间(21)。在画分层DFD时，应注意保持(22)之间平衡。DFD中从系统的输入流到系统的输出流的一连串连续变换形成一种信息交流，这种信息流可分为(23)两大类。

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Due to a constantly(71)environment, a poor understanding of the user's needs and preferences, as well as a(72)of willingness to modify(73)organizational structures and decision models, the full economic potential of Web.

 Information Systems(WIS)has not been realized by now. The data object types of the(74)meta. model, the Extended World Wide Web Design Technique(EW3DT), provide hypertext designers(75)a conceptual, user-centric framework and graphical notation for the construction of both, reference and customized models, during the software development process of commercial WIS. A reference model as a normative concept represents an abstraction of a typical company, its functional units, or its(Web)Information Systems and is intended to streamline the design and implementation of complex applications at reduced costs. As precondition for pursuing a partial globalization strategy, EW3DT distinguishes between technical and content-specific responsibilities for designing, implementing, and maintaining WIS.

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