this is often done with what we call an architectural hypen, a vertical hyphen or a horizontal hyphen, which is really a way of demonstrating a volume metric change between what is added and what is staying there. so defining things as volumes and not surfaces really matters. and the other thing to avoid is to have a sense that the volume is helping to continue through and in between the two of them and that also can make it look quite superficial. so articulating hyphens and that's an architectural thing and how it's detailed and how the materials are handled all really matters. so we're trying to get into specificity around these things. again, these are guidelines so it gives approaches and demonstrations and there's no specific means that is required. and the next one is a3.1, harmonize materials and new development with retained elements. so this is also i think goes hand-in-hand with a2.2, which is to articulate not only volume but material. and material often expresses and helps to express volume. and so in this case, i mean, there's rules of thumb around -- sometimes -- you do