> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# UnderlyingDescription

The **UnderlyingDescription** store contains the description of the [Crypto 2a underlying](../data-model-core/underlying).

The following table lists the fields in the store that are used for the Crypto 2a risk-class.
See the [UnderlyingDescription](../../../../../../datastore/standardisedapproach/underlying-desc) store documentation for details on the store.

| Data Model Field | Store Field      | Notes                        |
| ---------------- | ---------------- | ---------------------------- |
| As-Of Date       | AsOfDate         |                              |
| Underlying       | Underlying       |                              |
| Risk Class       | RiskClass        | “Crypto 2a”                  |
| Bucket           | Bucket           | Crypto asset                 |
| Location         | Crypto2aExchange | For delta and curvature only |

#### Note:

Crypto2aExchange is an optional datastore field, which is not required by the calculations.
It is disabled by default, in which case the exchange is not stored in the datastore explicitly, however it is still used during the ETL
to populate the Underlying and Risk Factor values.

To enable the addition of the optional Crypto2aExchange field in the **UnderlyingDescription** store, the configuration parameter 'frtb.crypto-2a.exchange-stored=true' needs to be added.