I try really hard not to buy into the "only allegorical" because I have seen a lot of things that people have told me "that's allegorical" and I later find three or four other paintings by different artists with the same elements. (One time someone told me the bodice and skirt was allegorical. I think I have over 25 paintings proving otherwise from the 16th c)

But in this case the outfit was just off from anything I'd ever seen before that I wasn't sure how real it was. (Like I said, masque gown!) But with the other drawings, I'm pretty sure I can make a descent case for it not being allegorical.