The annotations may perform a purely literary function, as is the case with The Annotated Alice: The Definitive Edition (1960)
but in other cases, they may be used to tell more of the story or provide insight into character. The Selected Work of T.S. Spivet (2009) by Reif Larsen is a good case in point.
Poetry lends itself to annotations, purely as a means of analyzing the text.
Our Challenge is to write a poem and provide annotations to the text, either as margin notes or footnotes. You may write a new poem for the challenge, or use a poem you have previously written which you think might lend itself to this approach. I realize this may cause some logistical problem in terms of formatting but the idea is to be creative rather than restrictive. I look forward to reading the results of this endeavour.