This code system http://devices.fhir.org/CodeSystem/MDC-designation-use defines the following codes:

Code	Display	Definition
synonym	Synonym	Synonym for reference identifier.
provisional-synonym	Synonym	Synonym for reference identifier that may be used for trial implementation and testing purposes.
deprecated-synonym	Synonym	Synonym for reference identifier that has been deprecated. The deprecated reference identifier should not be used.
systematic-name	Systematic name	An organization of differentiating, relational descriptors that are unique for each term.
common-term	Common term	Name that is in common use in medicine.
acronym	Acronym	English abbreviation of common term.