How to determine the appropriate system URL for a codable concept

[turbomam]

For example, what URL represents the NCIt as a system?

[turbomam]

there are examples in the Transform Notes Google Sheet but that doesn't show how to look up system URLs for other sources

[gaurav]

One option is that we could follow FHIR System identifiers (https://build.fhir.org/terminologies-systems.html) or NCIt concept identifiers (e.g. NCIT:C139307 for the GDC).

This is definitely a question for the CRDCH model, though, so I'm going to transfer it to that repo.