Database Objects [ACG]

DXF Group Codes

Advanced DXF Issues

Database Objects

AutoCAD drawings consist largely of structured containers for database objects. Database objects each have the following:

Handle whose value is unique to the drawing/DXF file, and is constant for the lifetime of the drawing. This format has existed since AutoCAD Release 10, but as of AutoCAD Release 13, handles are always enabled.
Optional xdata table, just as entities have had since AutoCAD Release 11.
Optional persistent reactor table.
Optional ownership pointer to an extension dictionary, which in turn owns subobjects placed in it by an application.

Symbol tables and symbol table records are database objects and, thus, have a handle. They can also have xdata and persistent reactors in their DXF records.