You can set an outline to display labels on every topic. These labels appear to the left of each topic’s triangle, and are automatically maintained by Opal (they are not editable text).
To set your outline’s display of labels:
Choose View > Labels. The Labels dialog appears. Here, you have four choices:
No labels.
Decimal style. This style is often used in scientific papers. Every level of indentation is expressed in the topic’s label as a number (with levels separated by a dot), where the number used is the topic’s (1-based) position among its sisters at that level.
Harvard style. This is the style you may have learned in school. The label consists of a single “number” (followed by a dot), expressing the topic’s position among its sisters. The style of this “number” varies from level to level: a Roman numeral at the top level, a capital letter at the second, an Arabic numeral at the third, and so on according to the convention.
Bullets. You enter a sequence of characters, with no separator between them. Your first character is used for all first-level topics, your second character is used for all second-level topics, and so on. If the number of levels in the outline exceeds the number of characters in your sequence, the last character in the sequence is used for those deeper levels.
These characters are used also in the text representation of an outline on the clipboard.
There is a preference for setting this character sequence for all future new outlines. Your setting in the Labels dialog overrides that preference, for this individual outline.
A label is regarded as part of the topic’s triangle. Thus, throughout this documentation, when you are told (for example) to double-click on a topic’s triangle, or to drag a topic by its triangle, you can equally well use the label if it is displayed.
Label display has an effect on the export of an outline: if labels are being displayed, they may be included in the exported version of the document.