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I notice on this page - http://build.fhir.org/terminologies-systems.html - that FHIR uses hl7/fhir URIs for a range of different code systems that don't have URIs - e.g. http://hl7.org/fhir/sid/icpc-2 and http://hl7.org/fhir/sid/ndc. Perhaps the same can be done for SNOMED 3.x and other deprecated code systems? For example http://hl7.org/fhir/sid/s3x. The only reason that this should be necessary for SNOMED RT is if an implementation uses SNOMED RT extension codes ... but if so, then something like http://hl7.org/fhir/sid/srt could be used. The documentation should also clearly indicate the deprecated status of these code systems. It may also be useful to add something to the 'Using SNOMED CT with FHIR' page (now https://terminology.hl7.org/SNOMEDCT.html ) page on the FHIR website that explains some of this history, including the deprecated nature of these code systems.
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