# The Asset Model

To avoid redundant data in transactions, the asset model is different for `CREATE` and `TRANSFER` transactions.

In a `CREATE` transaction, the `"asset"` must contain exactly one key-value pair. The key must be `"data"` and the value can be any valid JSON document, or `null`. For example:
```json
{
    "data": {
                "desc": "Gold-inlay bookmark owned by Xavier Bellomat Dickens III",
                "xbd_collection_id": 1857
            }
}
```

In a `TRANSFER` transaction, the `"asset"` must contain exactly one key-value pair. They key must be `"id"` and the value must contain a transaction ID (i.e. a SHA3-256 hash: the ID of the `CREATE` transaction which created the asset, which also serves as the asset ID). For example:
```json
{
    "id": "38100137cea87fb9bd751e2372abb2c73e7d5bcf39d940a5516a324d9c7fb88d"
}
```