This case-sensitive code system https://fhir.infoway-inforoute.ca/CodeSystem/aboriginalidentitytype defines the following codes:

Code	Display	English (English, en)
firstnations	First Nations	First Nations
inuit	Inuit	Inuit
metis	Metis	Metis
firstnations-inuit	First Nations and Inuit	First Nations and Inuit
firstnations-metis	First Nations and Metis	First Nations and Metis
firstnations-inuit-metis	First Nations, Inuit and Metis	First Nations, Inuit and Metis
inuit-metis	Inuit and Metis	Inuit and Metis