• For CDA → FHIR mapping
  • Translation to URLs is required for select OIDs defined here
  • For OIDs not in the above list and where no URL equivalent is known, add the urn:oid: prefix to OID

This wording makes it seem like only some ("select OIDs") OIDs require translation to URLs. Actually any code system must be mapped to a URL. If it's not on the select list linked, it might be present in terminology listing for a code system (since a code system can include its OID for non-FHIR systems).

Probably just need a 2nd bullet between these two like:

• Other coding systems may also exist in FHIR or FHIR implementation guides. If a code system documented somewhere contains an "OID for non-FHIR systems" (in the CodeSystem.identifier[system = urn:ietf:rfc:3986].value element), then its url should be used.

...or just rename the first link from "select OIDs defined here" to "known code systems available here and at terminology.hl7.org".