This is a mechanism that allows healthcare authorities to give the public the certainty that the APRN has demonstrated, prior to the granting of an APRN licence, the minimum competence to enter into practice in the field of roles and population of the APRN. If NSRCs practice in environments where they write prescriptions, for example. B an RNA capable of collaborating with a pain specialist, the RNA must have prescriptive authority and all requirements for the delegation of prescriptive authority must be met. These include requirements for an authority agreement or establishment protocol, as well as registration of medical delegation on the Texas Medical Board website. Where controlled substances are prescribed, the CRNA must also have the necessary registries for controlled substances (DEA and DPS).