Place Holder column is created in reports

A placeholder is a column for which you set the datatype and value in PL/SQL that you define. Placeholder columns are useful when you want to selectively set the value of a column (e.g., each time the nth record is fetched, or each time a record containing a specific value is fetched, etc.). You can set the value of a placeholder column in the following places: the Before Report Trigger, if the placeholder is a report-level column a report-level formula column, if the placeholder is a report-level column a formula in the placeholder's group or a group below it (the value is set once for each record of the group)