LibreOffice 7.5 Help
Click in a word, or select the words in your document that you want to use as an index entry.
Choose, and do one of the following:
To change the text that appears in the index, type the text that you want in the Entry box. The text that you type here does not replace the selected text in the document.
To add an index mark to similar words in your document, select Apply to all similar texts.
To add the entries to a custom index, click the New User-defined Index icon, enter the name of the index, and then click OK.
The best way to generate a table of contents is to apply the predefined heading paragraph styles, such as "Heading 1", to the paragraphs that you want to include in your table of contents.
Choose Numbering tab.and click the
Select the paragraph style that you want to include in your table of contents in the Paragraph Style box.
In the Level list, click the hierarchical level that you want to apply the paragraph style to.
Click OK. You can now apply the style to headings in your document and include them in your table of contents.