Oracle creates public synonyms for many data dictionary views so users can access
them conveniently. The security administrator can also create additional public
synonyms for schema objects that are used systemwide. Users should avoid naming
their own schema objects with the same names as those used for public synonyms.

数据字典视图的公共同义词
1. 用户通过公共同义词能方便的访问数据字典
2. 用户应防止自身的方案对象名与公共同义词名重复