It seems Airtable only supports dates that include a month and day, thus missing one key feature of ISO 8601 standard: the ability to use the same format for less precise dates, such as:
2018
2018-02
When I try entering these examples, Airtable automatically changes them to:
2018-01-01
2018-02-01
Supporting reduced-accuracy ISO-8601 dates would be nice. In the absence of this, users are forced to either enter incorrect data, or no data at all.