This code system http://hl7.org/fhir/version-algorithm defines the following codes:

Code Display Definition
semver SemVer Uses the semantic versioning scheme as defined in [semver.org](http://semver.org).
integer Integer Versions are integers and ordered numerically
alpha Alphabetical Simple alphabetic sort on a case-insensitive and accent-insensitive basis. (Sorting of different cases or accented versions of a character is indeterminate)
date Date Versions are expressed as an ISO date/time syntax (including syntaxes with only portions of a date)
natural Natural Sorted according to the algorithm defined here: [naturalordersort.org](http://www.naturalordersort.org/)
<status value="active"/> <experimental value="false"/> <date value="2021-01-05T10:01:24+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="Indicates the mechanism used to compare versions to determine which is more current."/> <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/version-algorithm"/> <content value="complete"/> <concept> <code value="semver"/> <display value="SemVer"/> <definition value="Uses the semantic versioning scheme as defined in [semver.org](http://semver.org)."/> </concept> <concept> <code value="integer"/> <display value="Integer"/> <definition value="Versions are integers and ordered numerically"/> </concept> <concept> <code value="alpha"/> <display value="Alphabetical"/> <definition value="Simple alphabetic sort on a case-insensitive and accent-insensitive basis. (Sorting of different cases or accented versions of a character is indeterminate)"/> </concept> <concept> <code value="date"/> <display value="Date"/> <definition value="Versions are expressed as an ISO date/time syntax (including syntaxes with only portions of a date)"/> </concept> <concept> <code value="natural"/> <display value="Natural"/> <definition value="Sorted according to the algorithm defined here: [naturalordersort.org](http://www.naturalordersort.org/)"/> </concept> </CodeSystem>