An explosion of interest in Non-Fungible Tokens (NFTs) has led to the emergence of vibrant online marketplaces that enable users to buy, sell and create digital assets. Largely considered contractual representations of digital artworks, NFTs allow ownership and authenticity to be proven through storing an asset and its associated metadata on a Blockchain. Yet, variation exists between chains, token protocols (such as the ERC-721 NFT standard) and marketplaces, leading to inconsistencies in the definitions and roles of token metadata. This research thus aims to define metadata in the context of NFTs, explore the boundary of metadata and asset data within tokens, and understand the variances and impacts these structures have on the curation of NFTs within online marketplaces and collections.