Autodesk CAD Drawing Exchange Format DXF

Autodesk CAD Drawing Exchange Format DXF

Autodesk CAD Drawing Exchange Format DXF is a ASCII text based vector data file format that has established itself as the industry standard in vector data interchange. Introduced from the leader industry leader in CAD applications it is definitely the widest spread standard for sharing CAD data.

DXF files are text files with caining multiple sections, where each section contains specific content.

ASCII versions of DXF can be read with a text-editor. The basic organization of a DXF file is as follows

HEADER section

General information about the drawing. Each parameter has a variable name and an associated value.

CLASSES section

Holds the information for application-defined classes whose instances appear in the BLOCKS, ENTITIES, and

OBJECTS sections of the database

Generally does not provide sufficient information to allow interoperability with other programs.

TABLES section

This section contains definitions of named items.

Application ID (APPID) table
Block Recod (BLOCK_RECORD) table
Dimension Style (DIMSTYPE) table
Layer (LAYER) table
Linetype (LTYPE) table
Text style (STYLE) table
User Coordinate System (UCS) table
View (VIEW)table
Viewport configuration (VPORT) table

BLOCKS section

This section contains Block Definition entities describing the entities comprising each Block in the drawing.

ENTITIES section

This section contains the drawing entities, including any Block References.

OBJECTS section

Contains the data that apply to nongraphical objects, used by AutoLISP and ObjectARX applications.

THUMBNAILIMAGE section

Contains the preview image for the DXF file.

The entities section contains the real geometry elements that describe the vector data. There are POINT ARC CIRCLE ELLIPSE LINE POLYLINE LWPOLYLINE SPLINE.
There are additional elements ton support 3D objects too.
Geometry data is organized by layers. You have the choice to display data by layer. Which is great for separating data considering its content.

Over the years AutoDesk added various AutoCAD specific extensions to the DXF vector fileformat to better support their own AutoCAD software.

DXF Specifications - Autodesk documentation on versions of DXF from Release 13 to current.

DXF not only stores the geometry elements, it also contains basic design attributes like linewidth, linestyle. Sufficient for plotting but not enough for all kinds of graphic applications.

CAD and vector data is present in all industries developing and manufacturing
real world products like cars, airplanes, computers,… everywhere you need CAD applications like AutoCAD and everywhere you have to exchange your vector data.