Entities in the database typically belong to a block table record. The block table contains three records by default, *MODEL_SPACE, *PAPER_SPACE, and *PAPER_SPACE0, which correspond to the three initial drawing spaces that can be edited directly by AutoCAD users. For examples of adding entities to the model space block table record, see Database Primer and Entities.
The *PAPER_SPACE and *PAPER_SPACE0 records correspond to the two predefined paper space layouts in AutoCAD. You can add, modify, and delete paper space layouts.
New block table records are created when the user issues a BLOCK command or an INSERT command to insert an external drawing. New block table records are also created with the acdbEntMake() function. The BLOCK? command lists the contents of the block table, with the exception of the *MODEL_SPACE and *PAPER_SPACE records. See Entities, for examples of block table record and block reference creation. (A block reference is an entity that refers to a given block table record.)