Carrier selection is achieved through the process of "allocation". As it's such a complex area, it's been given its own section in the FAQ.

This section has a number of commonly asked questions about the usage of the API itself.

These questions don't naturally fit into any of the other sections, but are still relevant to integrators.

Questions about the issues of integration itself.

Producing labels and supporting documentation

These questions are asked by people researching DM, and those who quickly need to refer to things.

Questions about standards and guidelines that are important for integration.

These questions concern the Test Centre systems, their purpose, and their usage.