These libraries are created by users to contain the Data Tables unique to an organization. Data Tables fall into three main classes:
- Common corporate data, used by several applications and many users but altered only by authorized users or specialized applications. Often, all such data is kept in one library and all applications look there. In some installations, there may be a hierarchy of corporate data, divisional data, departmental data, and so on.
- Application-specific user data, typically held in a separate library searched by only one stand-alone application or a group of related applications.
- Application-driving data, seen as data by the developer but not by the user. The user sees it as part of the system and typically does not manipulate it.
You can choose to place all application-driving data in one central library or place it in application specific libraries along with the user data. Both methods, and various compromises, are possible.
A typical application, then:
- learns its language from the System Library tables;
- finds its program in the Application Control TableLibrary and finds the Application Driving Tables in the Application Driving Tables Library; and
- operates on data from both corporate and private Data Table libraries.