the thematic focus or topic of the Throughline being explored

Each of the four Throughlines: Overall Story, Relationship Story, Main Character, and Impact Character, have a thematic topic which is described by its Issue. The Overall Story Issue, for example, provides a value standard for judging the Overall Story Characters' efforts in a story. Whatever kinds of things are done by the Overall Story Characters in relation to the Story Goal can be said to be linked thematically by this particular item.