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

CodeDisplayDefinition
semver SemVerUses the semantic versioning scheme as defined in [semver.org](http://semver.org).
integer IntegerVersions are integers and ordered numerically
alpha AlphabeticalSimple alphabetic sort on a case-insensitive and accent-insensitive basis. (Sorting of different cases or accented versions of a character is indeterminate)
date DateVersions are expressed as an ISO date/time syntax (including syntaxes with only portions of a date)
natural NaturalSorted 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>