AutoCAD DXF


AutoCAD DXF is a CAD data file format developed by Autodesk for enabling data interoperability between AutoCAD and other programs.
DXF was originally introduced in December 1982 as part of AutoCAD 1.0, and was intended to provide an exact representation of the data in the AutoCAD native file format, DWG, for which Autodesk for many years did not publish specifications. Because of this, correct imports of DXF files have been difficult. Autodesk now publishes the DXF specifications as a PDF on its website.
Versions of AutoCAD from Release 10 and up support both ASCII and binary forms of DXF. Earlier versions support only ASCII.
As AutoCAD has become more powerful, supporting more complex object types, DXF has become less useful. Certain object types, including ACIS solids and regions, are not documented. Other object types, including AutoCAD 2006's dynamic blocks, and all of the objects specific to the vertical market versions of AutoCAD, are partially documented, but not well enough to allow other developers to support them. For these reasons many CAD applications use the DWG format which can be licensed from Autodesk or non-natively from the Open Design Alliance.
DXF coordinates are always without dimensions so that the reader or user needs to know the drawing unit or has to extract it from the textual comments in the sheets.

File structure

ASCII versions of DXF can be read with any text editor. The basic organization of a DXF file is as follows:
; section
; section
; section
  1. Application ID table
  2. Block Record table
  3. Dimension Style table
  4. Layer table
  5. Linetype table
  6. Text style table
  7. User Coordinate System table
  8. View table
  9. Viewport configuration table
; section
; section
; section
; section
The data format of a DXF is called a "tagged data" format, which "means that each data element in the file is preceded by an integer number that is called a group code. A group code's value indicates what type of data element follows. This value also indicates the meaning of a data element for a given object type. Virtually all user-specified information in a drawing file can be represented in DXF format."