System Data

Background: Terminology, Thing/Node/Sequence/Element
Related: Name, Views, Hierarchy

When DBD initializes a new database, it adds data needed to boot and data frequently required by user. A portion of the system data is shown in the figure. Among other things, it includes the current database {db}, the system directory {system}, basic classes and their instances {not shown}. In general, do not delete or modify system data as this may make the database unbootable.

Db represents the current database. Db is an instance of the database class. Db serves as the root of the tree. Initially it displays one item, the system directory. In general, users will create data as items of db.

System is a directory. System is an instance of directory class. In general, the system directory stores system data.

User-Defined Directories:
User can create as many directories as desired and arrange them as seen fit. And an item can be listed in 0 to many directories. Each directory only contains a reference to the item and not the actual item itself.


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