The SUM clause establishes a Report Writer sum counter and names the
  data items to be summed.

  Format -

   {SUM {sum-name}...
       [UPON {detail-report-group-name} ... ]} ...

       [RESET ON { control-foot-name } ]
       [         { FINAL             } ]

1 - sum-name

  names a numeric data item with an optional sign in the File,
  Working-Storage, and Linkage Sections, or another sum counter
  in the Report Section.

2 - detail-report-group-name

  names a DETAIL report group.

3 - control-foot-name

  must reference a control-name in the report's CONTROL clause.