The overall organization of a DXF file is as follows:
CLASSES section. Holds the information for application-defined classes, whose instances appear in the BLOCKS, ENTITIES, and OBJECTS sections of the database. A class definition is permanently fixed in class hierarchy.
TABLES section. This section contains definitions for the following symbol tables.
APPID (application identification table)
BLOCK_RECORD (block reference table)
DIMSTYLE (dimension style table)
LAYER (layer table)
LTYPE (linetype table)
STYLE (text style table)
UCS (User Coordinate System table)
VIEW (view table)
VPORT (viewport configuration table)
- HEADER section. General information about the drawing is found in this section. It consists of an AutoCAD database version number and a number of system variables. Each parameter contains a variable name and its associated value.
ENTITIES section. This section contains the graphical objects (entities) in the drawing, including block references (insert entities).
OBJECTS section. Contains the nongraphical objects in the drawing. All objects that are not entities or symbol table records or symbol tables are stored in this section. Examples of entries in the OBJECTS section are dictionaries that contain mline styles and groups.
- BLOCKS section. Contains block definition and drawing entities that make up each block reference in the drawing.
If you use the Entities option of the DXFOUT command, the resulting DXF file contains only the ENTITIES section and the EOF marker. The ENTITIES section contains only the objects you select for output. If you select an insert entity, the corresponding block definition is not included in the output file.