File structureASCII versions of DXF can be read with any text editor. The basic organization of a DXF file is as follows:[3]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) tableBlock Record (BLOCK_RECORD) tableDimension Style (DIMSTYPE) tableLayer (LAYER) tableLinetype (LTYPE) tableText style (STYLE) tableUser Coordinate System (UCS) tableView (VIEW) tableViewport configuration (VPORT) tableBLOCKS 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.END OF FILEThe 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 (or record) type. Virtually all user-specified information in a drawing file can be represented in DXF format."[4]See also.dwg (DWG)Design Web Format (DWF)QCad, an open source CAD application that uses the DXF file format internally and to save and import filesLibreCAD, a version of QCAD Community Edition ported to Qt4Open Design Alliance (originally called OpenDWG)ShareCAD, a free online CAD viewer that supports DXF, among other formatsReferencesDXF specifications (PDF)FAQS.orgDXF File Structure"Chapter 1 -- DXF Format" Autodesk.comExternal linksAutoCAD DXF Reference (PDF version)AutoCAD DXF File Format SummaryAnnotated example DXF filePaul Bourke (March 1990). "Minimum Requirements for Creating a DXF File of a 3D Model".