This page is part of the FHIR Specification (v0.5.0: DSTU 2 Ballot 2). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R4 R3 R2
These system namespaces are defined for use in FHIR when representing codes that were defined as part of the v2 tables in FHIR instances. So if you are representing the code "M" from table 0001 in HL7 v2.3.1 in a FHIR instance, then you would use the system "http://hl7.org/fhir/v2/0001".
There are a number of subtle but serious issues with using tables defined for v2 as code systems, so some of these tables are mapped to a different namespace for each version. Note that even when multiple versions are mapped to the same namespace, there are additional underlying issues that mean that there are different formal code systems for different versions.
All of these namespaces are subject to further change as additional review of the v2 tables proceeds.