A run of content that is marked or highlighted, such as for reference purposes, or to call it out as having a special purpose.
If the marked content has an associated section in the document elaborating on the reason for the mark, then DETAILS should be used on the mark to point to that associated section. In addition, the reciprocal relation DETAILS_FOR should be used on the associated content section to point back to the mark. (Since: 2.36)