Model: ERC721ModelV1 > Alice wraps an ENS. Since there’s no corresponding collection, a collection (ENSCollectionV1) is created by cloning the ERC721ModelV1. > Bob wraps an ENS. Since we already now have an ENSCollectionV1, that collection will be used (no new collection is created if there’s already one available). > The model is updated: ERC721ModelV2 > Julian wraps an ENS. Since the ENSCollectionV1 was cloned from an older model version, a new collection is created: ENSCollectionV2. All subsequent ENS that are wrapped will be inserted here. > Older collections can be migrated to newer ones, by unwrapping all their ITEMs and wrapping them with the new Models.