edits to draft

Hi Yvonne, I made 2 small changes to your draft. 1) Instead of the word optional, I replaced it with the word rare as I think this is closer to the intended meaning. 2) I removed the comment, "feature is not currently used", as I think this may have been added in error as it didn't make sense to me in the context. Hope this is helpful, but if I've missed something, please just reverse my changes. Cheers, Katherine