1. How do other core projects address tourists and foreign passports holders? for example, In Canada, they've defined only Canadian passports by adding a passport slice that has a fixed URI for Canadian passports.
2. How can we define a dynamic pattern to support all passports?
After looking at other cores and also consulting the FHIR community, it seem like we are the first to try and handle foreign passports with a dynamic URI. We found an open ticket mentioning the issue and it contained a suggested solution.
After consulting with Lloyd we decided to adopt that suggestion and added a dedicated slice for it. The system URI is bounded to a ValueSet holding all countries URI's. The pattern is: http://hl7.org/fhir/sid/passport-[xxx] where [xxx] is the country's ISO-3166 3-letter code. Examples: http://hl7.org/fhir/sid/passport-AUS http://hl7.org/fhir/sid/passport-USA http://hl7.org/fhir/sid/passport-ISR