Annotations added by users to displayed text should be distinguishable from the text itself.
Additional Information:
This recommendation refers to additions such as marginal notes on printed displays. Other annotation such as format control characters might be shown in a special display mode where text has been expanded to permit annotation between lines. For example, continuous annotation might be displayed in the top and/or bottom lines of a page, separated from the text by blank lines; optional annotation might be displayed in window overlays.