A long worksheet can be easier to read when supporting rows collapse beneath a visible summary. The group boundary matters: including the summary row in the group can hide the very figure the reader needs. Plan the visible result before selecting a large range.

In a copy of the sheet, identify one small section with detail rows followed by a total. Check that the total's formula already includes the intended detail. Grouping changes how rows are displayed; it should not be used to repair a broken calculation.

Build one group with a clear boundary

Select only the supporting rows for that section. Use Data, Group and Outline, Group, and choose rows when Calc asks which dimension to group. Keep the summary row outside the selected detail block.

Collapse the group using its outline control. Confirm that the section label and summary remain visible. Expand it again and inspect the first and last detail records. This catches an off-by-one selection that might hide a neighbouring heading or leave one supporting row outside the group.

Repeat with another section only after the first works. Keep each group understandable before introducing nested groups. A complex hierarchy is harder to maintain when the worksheet regularly gains rows or subtotals.

Distinguish hidden detail from removed data

Calc's Show Details and Hide Details commands operate on the outlined rows or columns. Selecting the outlined table lets you reveal its groups for inspection. Ungroup changes the grouping arrangement; removing an outline does not mean deleting the supporting records.

Compare the summary before and after collapsing. Investigate any unexpected change rather than assuming that hidden rows should automatically leave every calculation. The correct behaviour depends on the formulas used and the intended report definition.

Before sharing the editable workbook, assume recipients can reveal its retained detail. An outline is a reading aid, not a privacy boundary. If only an approved summary may leave the organisation, prepare and inspect a separate release artifact containing that permitted information.

After inserting new records later, repeat the boundary check. Keep the summary visible, confirm all intended detail expands, and verify the total covers the new entries. That small maintenance step preserves a useful outline as the sheet grows.

Reference: LibreOffice documentation.