The start section is an unformatted prologue to the IGES file that is used to indicate certain conventions within the file (for example, what type of information is included in a specific group of layers). All records in the section have the letter S in Column 73 and a sequence number in Columns 74 through 80. The information in Column 1 through 72 need not be formatted in any special way except that the ASCII character set must be used.
The IGES specification does not contain any recommendations regarding the use of this section. Note that several CAD systems do not allow the user to write information to this section.
An example of the start section is given below:
Cimatron Iges convertor S 1