Headings that start topics, or to which you assign the Contents property or a contents level, are automatically included in the contents; see the following:
§7.4.3 Including contents entries in HTML-based Help.
§7.4.4 Setting contents levels for HTML-based Help.
However, if you set the following option, links might be missing for contents entries that are not topic headings:
[JavaHelpOptions] or [OracleHelpOptions]
This is mainly an issue for JavaHelp, where anchors in text cause unwanted spacing; see §11.9 Linking to destinations within topics.