Another use-case for recently found property - using spent boxes as proof in ergo script:
An NFT collection is a category to which some NFTs belong. In the simplest case, an artist can have a “modern arts” collection and mint his modern arts in that collection. This way, an artist can have multiple collections to better present his artworks. This thread is a solution on how to handle collections in a decentralized way on Ergo.
Let’s consider each collection as an NFT on the blockchain with some properties like collection name, description, cover image, etc.
The artist can create a collection NFT and own it in his wallet. Once he wants to mint an artwork in that collection, he can simply mint the NFT by putting the box containing the collection NFT in the first input of his minting transaction. The artwork NFT ID will be equal to the box ID containing the collection NFT. This way, not only it is possible to verify that artwork belongs to a specific collection off-chain, but also it is possible to do so in ergo script. The way to do that is by simply providing the spent collection box to the contract, then the artwork NFT ID must be equal to the provided box’s ID and the provided box must include the collection NFT. It is obvious that no one but the artist can mint artwork in that collection!