# Understanding these transactions

Source: https://developer.avalara.com/ecommerce-integration-guide/test-transactions/understanding-these-transactions/

The examples in this section are based on the Nexus settings that are described in the [Create and activate a company](/ecommerce-integration-guide/configure-your-avatax-account/create-and-activate-a-company-sales-tax) topic. If you set up your test company the same way, you'll see the same responses when you run these examples. In addition, the examples in this section are broken out into Core requirements and Refunds.

-   All integrations must review the Core requirements examples.

-   If you're also attempting to get certified in the Refunds advanced feature, then review and run the Refunds examples.