As suggested by @Smalyshev, units may be enough.
See https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/master/repo/includes/Rdf/Values/QuantityRdfBuilder.php
Description
Description
| Status | Subtype | Assigned | Task | ||
|---|---|---|---|---|---|
| Open | None | T173750 Handle complex data types | |||
| Resolved | Hjfocs | T173760 Handle quantity data values |