Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Currency | Code | Entry ERM II | Central rate | Official target date |
| --- | --- | --- | --- | --- |
| Bulgarian lev | BGN | — | 1.95583 | — |
| Croatian kuna | HRK | — | — | — |
| Czech koruna | CZK | — | — | — |
| Danish krone | DKK | 1 January 1999 | 7.46038 | Formal opt-out |
| Hungarian forint | HUF | — | — | — |
| Latvian lats | LVL | 2 May 2005 | 0.702804 | 1 January 2014 |
| Lithuanian litas | LTL | 28 June 2004 | 3.45280 | 1 January 2015 |
| Polish złoty | PLN | — | — | — |
| Romanian leu | RON | — | — | — |
| Swedish krona | SEK | Not considered | — | De facto opt-out |
| British pound sterling Gibraltar pound | GBP GIP | Not considered | — | Formal opt-out |
Question:
What type of currency has a code of SEK?
Answer:
Swedish krona