This code system http://hl7.org/fhir/title-type defines the following codes:

CodeDisplayDefinition
primary Primary titleMain title for common use. The primary title used for representation if multiple titles exist.
official Official titleThe official or authoritative title.
scientific Scientific titleTitle using scientific terminology.
plain-language Plain language titleTitle using language common to lay public discourse.
subtitle SubtitleSubtitle or secondary title.
short-title Short titleBrief title (e.g. 'running title' or title used in page headers)
acronym AcronymAbbreviation used as title
earlier-title Different text in an earlier versionAlternative form of title in an earlier version such as epub ahead of print.
language Different languageAdditional form of title in a different language.
autotranslated Different language derived from autotranslationMachine translated form of title in a different language, language element codes the language into which it was translated by machine.
human-use Human useHuman-friendly title
machine-use Machine useMachine-friendly title
duplicate-uid Different text for the same object with a different identifierAn alternative form of the title in two or more entries, e.g. in multiple medline entries
<status value="active"/><experimental value="false"/><date value="2020-12-28T16:55:11+11:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="Used to express the reason and specific aspect for the variant title, such as language and specific language."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/title-type"/><content value="complete"/><concept><code value="primary"/><display value="Primary title"/><definition value="Main title for common use. The primary title used for representation if multiple titles exist."/></concept><concept><code value="official"/><display value="Official title"/><definition value="The official or authoritative title."/></concept><concept><code value="scientific"/><display value="Scientific title"/><definition value="Title using scientific terminology."/></concept><concept><code value="plain-language"/><display value="Plain language title"/><definition value="Title using language common to lay public discourse."/></concept><concept><code value="subtitle"/><display value="Subtitle"/><definition value="Subtitle or secondary title."/></concept><concept><code value="short-title"/><display value="Short title"/><definition value="Brief title (e.g. 'running title' or title used in page headers)"/></concept><concept><code value="acronym"/><display value="Acronym"/><definition value="Abbreviation used as title"/></concept><concept><code value="earlier-title"/><display value="Different text in an earlier version"/><definition value="Alternative form of title in an earlier version such as epub ahead of print."/></concept><concept><code value="language"/><display value="Different language"/><definition value="Additional form of title in a different language."/></concept><concept><code value="autotranslated"/><display value="Different language derived from autotranslation"/><definition value="Machine translated form of title in a different language, language element codes the language into which it was translated by machine."/></concept><concept><code value="human-use"/><display value="Human use"/><definition value="Human-friendly title"/></concept><concept><code value="machine-use"/><display value="Machine use"/><definition value="Machine-friendly title"/></concept><concept><code value="duplicate-uid"/><display value="Different text for the same object with a different identifier"/><definition value="An alternative form of the title in two or more entries, e.g. in multiple medline entries"/></concept></CodeSystem>