If a delete record operation is performed on a record in an ADT table, the record is not physically removed from the table. The record is, however, logically removed from the table. Deleted records in an ADT table are not visible to the application. Deleted records cannot be "un-deleted" or "recalled". The space used by records deleted from the table are marked for record re-use. That is, a subsequent append or insert operation will use space marked for re-use before using new space at the end of the table for a new record. Thus, the size of an ADT table will not increase after an append or insert operation if there is space marked for re-use in the table.
If the Pack operation is performed on a table, space marked as available for record re-use will be physically removed from the table.