You can specify windowed date fields as sort keys if your version of DFSORT supports the Y2PAST option. If so, DFSORT can sort or merge on the windowed date sequence.
To sort on a windowed date field, use the DATE FORMAT clause to define a windowed date field; then use the field as the sort key. DFSORT will use the same century window as that used by the compilation unit. Specify the century window with the YEARWINDOW compiler option.
DFSORT supports year-last windowed date fields, although the compiler itself does not provide automatic windowing for year-last windowed date fields in statements other than MERGE or SORT.
related concepts
Millennium language extensions (MLE)
related tasks
Sorting and merging by date
related references
YEARWINDOW
DATE FORMAT clause (Enterprise COBOL Language Reference)
DFSORT Application Programming Guide (OPTION control statement: Y2PAST)