bigchaindb/docs/server/source/data-models/asset-model.md

The Digital Asset Model

The asset ID is the same as the ID of the CREATE transaction that defined the asset.

In the case of a CREATE transaction, the transaction ID is duplicated into the asset object for clarity and consistency in the database. The CREATE transaction also contains a user definable payload to describe the asset:

{
    "id": "<same as transaction ID (sha3-256 hash)>",
    "data": "<json document>"
}

For TRANSFER transactions we only keep the asset ID:

{
    "id": "<asset's CREATE transaction ID (sha3-256 hash)>"
}

• id: The ID of the CREATE transaction that created the asset.
• data: A user supplied JSON document with custom information about the asset. Defaults to null.