Rearranging the DataWindow object – PB Docs 2017

When you create a group, PowerBuilder creates two new bands
for each group:

The bar identifying the band contains:

You can include any control in the DataWindow object (such as
columns, text, and computed fields) in the header and trailer bands
of a group.

Using the group header
band

The contents of the group header band display at the top of
each page and after each break in the data.

Typically, you use this band to identify each group. You might
move the grouping column from the detail band to the group header
band, since it now serves to identify one group rather than each
row.

For example, if you group the rows by department and include
the department in the group header, the department will display
before the first line of data each time the department
changes.

At runtime, you see this:

Suppressing group
headers

If you do not want a group header to display at the top of
each page when you print or display a report, select the Suppress
Group Header check box on the General property page for the header.
If none of the headers are suppressed, they all display at the top
of each page. When a page break coincides with a group break, the
group header and any group headers that follow it display even if
the Suppress Group Header property is set, but higher level headers
are suppressed if the property is set for those headers.

For example, suppose a report has three groups: division,
sales region, and sales manager. If all three group headers are
suppressed, and a sales region group break coincides with a page
break, the division header is suppressed but the sales region and
sales manager headers display.

Using the group trailer
band

The contents of the group trailer display after the last row
for each value that causes a break.

In the group trailer band, you specify the information you
want displayed after the last line of identical data for each value
in the group. Typically, you include summary statistics here, as
described next.