the first is addition. this is a new detail added to give the reader or viewer a new understanding of the story. this detail would not have been planned when a series was first being made. for example, many people who watched complained that the death star had an easily spotted and poorly placed weak point. this made it easier to be destroyed. george lucas, the writer of star wars, did not have an explanation why. however, the writers of its prequel, rogue one, later explained this. they wrote the story so that character galen erso, who is the main character jyn erso's father, made its weak point easily seen and poorly placed on purpose. he did this so he could help the rebel alliance destroy it.