Future enhancement add support for multiple calendars (e.g. Julian calendar)

[mzeinstra]

The current implementation is based on the Gregorian calendar. But there are other calendars with slight different structures. It is good to research how we can support those calendars as well. Current Wikidata DateTime also accepts the Julian calendar.

From a historic perspective we might want to present dates as they are presented on historical documents, not translated to how we now would date them.

This is an epic ticket to document possible future development and has no priority at the moment.

Creating additional calendar might help the adoption of EDTF in Wikibase. See https://phabricator.wikimedia.org/T207705

[Hefaistos68]

ISO 8601-2:2019 section 1 specifically states that it "excludes the representation of date elements from non-Gregorian calendars, or times not from the 24-hour clock."

So, any extension to support other calendars would be nice but violating the standard.

[mzeinstra]

Thank you @Hefaistos68 for this documentation. The issue was created due to the availability of different calendars in Wikidata for 'normal' datetime. We understand that that might extending the extended date time format :)