Using national groups

The following data description entry specifies that a level-01 group and its subordinate groups are national group items:

01  Nat-Group-1    GROUP-USAGE NATIONAL.
    02  Group-1.
        04  Month    PIC 99.
        04  DayOf    PIC 99.
        04  Year     PIC 9999.
    02  Group-2    GROUP-USAGE NATIONAL.
        04  Amount   PIC 9(4).99  USAGE NATIONAL.

In the example above, Nat-Group-1 is a national group, and its subordinate groups Group-1 and Group-2 are also national groups. A GROUP-USAGE NATIONAL clause is implied for Group-1, and USAGE NATIONAL is implied for the subordinate items in Group-1. Month, DayOf, and Year are national decimal items, and Amount is a numeric-edited item that has USAGE NATIONAL.

You can subordinate national groups within alphanumeric groups as in the following example:

01  Alpha-Group-1.
    02  Group-1.
        04  Month   PIC 99.
        04  DayOf   PIC 99.
        04  Year    PIC 9999.
    02  Group-2   GROUP-USAGE NATIONAL.
        04  Amount  PIC 9(4).99.

In the example above, Alpha-Group-1 and Group-1 are alphanumeric groups; USAGE DISPLAY is implied for the subordinate items in Group-1. (If Alpha-Group-1 specified USAGE NATIONAL at the group level, USAGE NATIONAL would be implied for each of the subordinate items in Group-1. However, Alpha-Group-1 and Group-1 would be alphanumeric groups, not national groups, and would behave like alphanumeric groups during operations such as moves and compares.) Group-2 is a national group, and USAGE NATIONAL is implied for the numeric-edited item Amount.

You cannot subordinate alphanumeric groups within national groups. All elementary items within a national group must be explicitly or implicitly described as USAGE NATIONAL, and all group items within a national group must be explicitly or implicitly described as GROUP-USAGE NATIONAL.