DETAIL report groups can be structured into a nested set of control groups. Each control group can begin with a CONTROL HEADING report group and end with a CONTROL FOOTING report group.
When nested control groups are defined, the recognition of a change in value of a control data item in a control hierarchy is called a control break and the heading and footing lines associated with the control data-name are called CONTROL HEADING and CONTROL FOOTING report groups.
During the execution of a GENERATE statement, the RWCS uses the control hierarchy to check automatically for control breaks. If a control break has occurred, all controls that are minor to it are considered to have changed, even though they may not in fact have changed. The occurrence of a control break causes the following sequence of events to take place: