Representing incomplete birth/death dates

[SvenLieber]

How do we represent incomplete dates in our RDF-based data model?

There seems to be no single standard way to represent uncertain or incomplete dates. We have seen in the data source KBR authors that several incomplete date values exist (see #5 )

• A longer discussion for schema.org: https://github.com/schemaorg/suggestions-questions-brainstorming/issues/219
• A discussion on valid dates at SEMIC which discourages incomplete dates in XSD: http://mapping.semic.eu:81/vdm/description.vsp?namespace=cv&type=8cf10d2341ed01492506085688270c1e&id=&format=
• Years can be represented with the datatype xsd:gYear, but no centuries
• As mentioned in the schema.org discussion, OWLTime became a W3C candidate recommendation and can be used to represent open ended intervals
• The Library of Congress adopted a standard to represent dates with different precision: EDTF https://github.com/SvenLieber/beltrans-data/issues/5#issuecomment-896085692
• According to the following issue there is not yet a RDF representation of EDTF: https://github.com/silknow/converter/issues/66
• Someone created a draft ontology for EDTF by using OWLTime: https://periodo.github.io/edtf-ontology/

I'm wondering if, instead of an ontology solution with new properties, a datatype could be introduced using the specified string notation by EDTF and then semantically be defined using something like QUDT?

[AnnVanCamp]

Could we adopt the same solution as in Luxembourg? See Factsheet – Luxembourg Shared Authority File (received by mail): "Wikibase contains a datetime representation based on ISO 8601:2004. The project extended the Wikibase software that includes ISO 8601:2019, and their extensions. This resulted in two open source products. A library for the validation and humanisation of EDTF dates in PHP, and an extension to WikiBase to use this library. Both are available as open source software for all to use and improve. The humanisation is translated in various languages using Translate.wiki."