This is the ValueSet that contains all the codes in eCTD sections Terminology (http://hl7.org/fhir/us/pq-cmc-fda/ValueSet/cmc-comp-section-types-vs) and Document Section Codes (http://hl7.org/fhir/ValueSet/doc-section-codes). E.g. what you have to deal with if you get resources containing codes in either of them