IGES File Format Specification: S Section
S (Start) SectionAs for all sections each line is divided into 3 "columns". The first column (characters 1-72) in the S section can contain any text, the second column (character 73) just contains the letter S to denote that this is the S section and the third column (characters 74-80) contains a right-justified number which is the line number within the S section. In the example below these are numbers 1,2,3 and 4. The space in front of the S section line numbers can be padded with zeroes but this is not compulsory. The number of lines in the S section is defined in the T section.
For example in the S section:
IGES FILE DATA SOURCE = DDN PART S 1 ICEM PART NAME = S 2 1POINT.IGS S 3 ICEM PART SHEET NUMBER = 1 S 4
The corresponding T section (the last line of the IGES file) might be:
S 4G 4D 20P 13T 1i.e. the S section contains 4 lines.