An argument is a formal prose or poetic description of the contents of a text or section of text (such as a chapter or essay). Arguments are often labelled as such (“The Argument”) but not always.
The WWP encodes arguments using the TEI <argument> element.
<argument><p>In which Pooh finds that bees make honey...</p></argument>
<p>Pooh was walking in the Seven Acre Woods...</p>
<l>Acrasia here is seen in much disgrace;</l>
<l>Sad tears flow freely down her pearly face;</l>
<l>But Artagrax will heal her wretched plight,</l>
<l>And bear her off to glory in his sight.</l>