Drawing Interchange File Formats ASCII DXF File Format

General File Structure

Group Codes

Group codes and the associated values define a specific aspect of an object or entity. The line immediately following the group code is the associated value. This value can be a a string, an integer, or a floating-point value, such as the X coordinate of a point. The lines following the second line of the group, if any, are determined by the group definition and the data associated with the group.

Special group codes are used as file separators, such as markers for the beginning and end of sections, tables, and the end of the file itself.

Entities, objects, classes, tables and table entries, and file separators are introduced with a 0 group code that is followed by a name describing the group.

The maximum DXF file string length is 256 characters. If your AutoCAD drawing contains strings that exceed this number, those strings are truncated during DXFOUT. DXFIN fails if your DXF file contains strings that exceed this number.

ASCII Control Characters

DXFOUT handles ASCII control characters in text strings by expanding the character into a caret (^) followed by the appropriate letter. For example, an ASCII Control-G (BEL, decimal code 7) is output as ^G. If the text itself contains a caret character, it is expanded to caret, space (^ ). DXFIN performs the complementary conversion.