What does "1 piece whole orange, zested" mean

Hi - thanks for the question and a good one to that. Since publishing that recipe the format over here has changed. Didn't think of changing all my recipes. Anyhow ... that would be one whole orange (normal size) zested. This is a great cake. Enjoy!

Perhaps the author will respond, but I take it to mean zest of one whole orange. Of course oranges come in different sizes (and flavors) so you may just have to use your own judgement.