edtf-date.biblatex

@article{item3-3, date={1998/unknown}}
@article{item3-4, date={1999/open}}
@article{item3-10, date={2004-04-05T14:34:00}}
@article{item5-1, date={0000}}
@article{item5-2, date={-0876}}
@article{item5-3, date={-0877/-0866}}
@article{item5-5, date={-0343-02}}
@article{item5-8, date={1723~}}
@article{item5-9, date={1723?}}
@article{item5-10, date={1723?~}}
@article{item5-11, date={2004-22}}
@article{item5-12, date={2004-24}}
@article{item5-13, date={20uu}}
@article{item5-14, date={y-123456789}}

---
references:
- id: item3-3
  type: article-journal
  issued:
  - year: 1998
  - {}

- id: item3-4
  type: article-journal
  issued:
  - year: 1999
  - {}

- id: item3-10
  type: article-journal
  issued:
  - year: 2004
    month: 4
    day: 5

- id: item5-1
  type: article-journal
  issued:
  - year: -1

- id: item5-2
  type: article-journal
  issued:
  - year: -877

- id: item5-3
  type: article-journal
  issued:
  - year: -878
  - year: -867

- id: item5-5
  type: article-journal
  issued:
  - year: -344
    month: 2

- id: item5-8
  type: article-journal
  issued:
  - year: 1723
    circa: true

- id: item5-9
  type: article-journal
  issued:
  - year: 1723

- id: item5-10
  type: article-journal
  issued:
  - year: 1723
    circa: true

- id: item5-11
  type: article-journal
  issued:
  - year: 2004
    season: 2

- id: item5-12
  type: article-journal
  issued:
  - year: 2004
    season: 4

- id: item5-13
  type: article-journal
  issued:
  - year: 2000
  - year: 2099

- id: item5-14
  type: article-journal
  issued:
  - year: -123456790
...