In the HL7 Terminology Authority (HTA) meeting held on 10 June 2020 it agreed that the following note should be removed from the Terminologies page of the FHIR Core specification:

UMLS Note: The UMLS includes many code systems that do not have an entry in the table below, or in the HL7 OID registry, or on http://registry.fhir.org. Until these code systems are registered, implementers may use the pattern http://www.nlm.nih.gov/research/umls/[SAB], where [SAB] is the lowercase of abbreviation of the code system as provided by UMLS. e.g. The system for "Multum MediSource Lexicon" would then be http://www.nlm.nih.gov/research/umls/mmsl. Implementers choosing to use this pattern should be aware that very often, when the code system is registered, it will use a different system.