What specific country wording is accepted by VSure for VEVO Checks

The vSure API accepts the ISO 3166-1 Alpha-3 country codes: List of ISO 3166 country codes - Wikipedia. 

And the following is the list of the acceptable country names that can be used as part of the request data, aligned to the Home Affairs VEVO service:

Department Of Home Affairs Country List Mapped To ISO 3 Code