HL7 Specification: Characteristics of a Value Set Definition, Release 1 approved by ANSI March 1 2019 .
This document describes the data elements that formally define and characterize (describe) how to create an HL7 conformant value set. These include: the metadata used to identify and define a value set definition, example functions that can be used to construct a value set definition expression which defines the intended coded content, elements to support value set definition versioning. It includes an informative discussion on the necessary value set expansion that is the result of evaluation of a value set definition.
http://www.hl7.org/implement/standards/product_brief.cfm?product_id=437 for more information.