Design Exchange Specification (DES) format describes degree 1 curves Polylines in DES format require less disk space than the same data in IGES format.

The file structure is as follows:

• The START line indicates the linear units system that is used.
• The HEADER line contains a reference to the Userinfo.
• The SENDING SYSTEM line indicates the type of preprocessor used.
• The LINE indicates the start of a description of edit points for constructing a first degree line. The parameters are grouped by three and represent the X,Y and Z coordinates of the points that form the edit point of the lines. A new description of a line always starts with the LINE entity, followed by the number of lines, the number of edit points and a 0 to finish.
• The DES file concludes with a * TERMINATE section.
• Every line ends with a line number.