!!! Overview[1] [2]
[{$pagename}] Data elements and interchange formats – Information interchange – Representation of [dates|DateTime] and [times|DateTime] is an international standard covering the exchange of [date] and [time]-related [data].


[ISO 8601] prescribes, as a minimum, a four-digit [{$pagename}] [YYYY] to avoid the year [2000|Year 2000] problem. [ISO 8601] therefore represents years from 0000 to 9999, year 0000 being equal to 1 [BC] and all others [AD]. 

!! Except
However, years prior to [Year 1582] are __NOT__ automatically allowed by the standard. Instead "values in the range 0000 through [Year 1582] shall only be used by mutual agreement of the partners in information interchange."

To represent years before 0000 or after 9999, the standard also permits the expansion of the year representation but only by prior agreement between the sender and the receiver. An expanded year representation [±YYYYY] must have an agreed-upon number of extra year digits beyond the four-digit minimum, and it must be prefixed with a + or − sign instead of the more common [AD]/[BC] (or [CE]/[BCE]) notation; by convention 1 BC is labelled +0000, 2 BC is labeled −0001, and so on.


!! [Examples]
%%zebra-table
%%sortable
%%table-filter
||Example||Description
|[Date] Only|2018-07-09
|Combined [date and time|Timestamp] in UTC|Any of these:\\ 2018-07-09T13:34:38+00:00 \\2018-07-09T13:34:38Z\\20180709T133438Z
|[Week]|2018-W28
|[Date] with [week] number|2018-W28-1
|[Date] without [year]|--07-09 (last in ISO8601:2000, in use by [RFC 6350])
|Ordinal date|2018-190
/%
/%
/%


!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [ISO_8601|Wikipedia:ISO_8601|target='_blank'] - based on information obtained 2016-11-23- 
* [#2] - [Year|Wikipedia:Year|target='_blank'] - based on information obtained 2017-10-14-