Reference to an object within the document (for example, a table, a bibliographic citation).
Any combination of:
Text, numbers, or special characters
<bold> Bold
<italic> Italic
<monospace> Monospace Text (Typewriter Text)
<overline> Overline
<roman> Roman
<sans-serif> Sans Serif
<sc> Small Caps
<strike> Strike Through
<underline> Underline
<named-content> Named Special (Subject) Content
<styled-content> Styled Special (Subject) Content
<sub> Subscript
<sup> Superscript