COBOL Standard

Standard COBOL (as defined in the About ILE COBOL Programmer's Guide) consists of eleven functional processing modules, seven of which are required and five of which are optional.

The seven required modules are: Nucleus, Sequential I-O, Relative I-O, Indexed I-O, Inter-Program Communication, Sort-Merge, and Source Text Manipulation. The five optional modules are: Intrinsic Function, Report Writer, Communication, Debug, Segmentation.

Language elements within the modules may be classified as level 1 elements and level 2 elements. Elements within nine of the modules are divided into level 1 elements and level 2 elements. Three of the modules (SORT-MERGE, REPORT WRITER, and INTRINSIC FUNCTION) contain only level 1 elements. For instance, Nucleus level 1 elements perform basic internal operations. Nucleus level 2 elements provide for more extensive and sophisticated internal processing.

The three subsets of Standard COBOL are the high subset, the intermediate subset, and the minimum subset. Each subset is composed of a level of the seven required modules: Nucleus, Sequential I-O, Relative I-O, Indexed I-O, Inter-Program Communication, Sort-Merge, and Source Text Manipulation. The five optional modules (Intrinsic Function, Report Writer, Communication, Debug and Segmentation) are not required in the three subsets of Standard COBOL.
  • The high subset is composed of all language elements of the highest level of all required modules. That is:
    • Level 2 elements from Nucleus, Sequential I-O, Relative I-O, Indexed I-O, Inter-Program Communication, and Source Text Manipulation
    • Level 1 elements from Sort-Merge.
  • The intermediate subset is composed of all language elements of level 1 of all required modules. That is:
    • Level 1 elements from Nucleus, Sequential I-O, Relative I-O, Indexed I-O, Inter-Program Communication, Sort-Merge, and Source Text Manipulation.
  • The minimum subset is composed of all language elements of level 1 of the Nucleus, Sequential I-O, and Inter-Program Communication modules.

The five optional modules are not an integral part of any of the subsets. However, none, all, or any combination of the optional modules may be associated with any of the subsets.