Central redundancy-free information repository for all application and system data in the R/3 System. The ABAP Dictionary describes the logical structure of application development objects such as tables, views and data types, as well as their representation in the structures of the underlying relational database. Since all runtime environment components such as application programs or the database interface get information about these objects directly from the ABAP Dictionary, data redundancy is eliminated. The ABAP Dictionary is an active data dictionary and is fully integrated in the ABAP Workbench.
－－－－－－－－－－－－－－－－－－－－－－分隔线上面是 SAP 标准文档中提供的说明
分隔线下面是我的翻译
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ABAP 字典是 R/3 系统中所有应用和系统数据的无冗余的信息知识库。ABAP 字典描述了表、视图和数据类型等应用开发对象的逻辑结构，以及它们在后台关系数据库中表现的结构。由于所有运行时环境的组件，比如应用程序或者数据库接口，都从 ABAP 字典中直接获取这些对象的信息，也就消除了数据冗余。ABAP 字典是一个活跃的数据字典，完全集成在 ABAP 工作台中。