OwnedTokens

OwnedTokens refers to the set or collection of tokens that are owned by a particular account within a tokenized system, typically on a blockchain. In practice, it denotes the data structures and logic used to track which tokens belong to which addresses, supporting operations such as balance queries, listings, and transfers. OwnedTokens is a common concept across fungible and non-fungible token standards, with nuances depending on the token type.

In fungible token standards (such as ERC-20), ownership is usually represented as a balance per address rather than a per-token list. In non-fungible token standards (such as ERC-721), ownership is tracked on a per-token basis, and systems often expose a way to enumerate or list the tokens owned by an address. The ERC-721Enumerable extension, for example, provides mechanisms to enumerate an owner's tokens, enabling wallets and marketplaces to display a user’s holdings.

Common implementation approaches include mappings from addresses to token collections, and mappings from token identifiers to owners. Some designs also maintain reverse indices or per-owner arrays to enable efficient lookups and enumeration. However, maintaining exhaustive per-owner collections on-chain can add gas costs, so many deployments rely on off-chain indexing or rely on standard interfaces for on-demand queries.

Security considerations for ownedTokens include ensuring consistency during transfers, minting, and burning, and preventing duplicate ownership records. Correctly updating all related indices during state changes is critical to avoid misreported holdings or unauthorized transfers.

Use cases for ownedTokens include wallet displays, marketplace listings, airdrops, and provenance tracking. The concept is central to understanding how token ownership is represented and queried in decentralized applications. See also ERC-721, ERC-721Enumerable, ERC-1155, and token ownership models.