system for member insurance identifier

[gonatf]

https://hl7.org.au/fhir/4.1.0/StructureDefinition-au-insurancemembernumber.html needs guidance on a system to use for insurance member identifiers.

Could use something like http://ns.electronichealth.net.au/id/insurer-scoped/membernumber/1.0/{insurer-code}

where insurer-code comes from

https://www.privatehealth.gov.au/dynamic/insurer

[brettesler-ext]

Could this be added to comments of existing issue https://jira.hl7.org/browse/FHIR-46321