Editing ISO 8601 (section)

==Time intervals==
{| class="infobox" style="text-align:center; width:23em"
|-
| <start>/<end>
|-
| <start>/<duration>
|-
| <duration>/<end>
|-
| <duration>
|}
A time interval is the intervening time between two time points. The amount of intervening time is expressed by a duration (as described in the previous section). The two time points (start and end) are expressed by either a combined date and time representation or just a date representation.

There are four ways to express a time interval:

#Start and end, such as "2007-03-01T13:00:00Z/2008-05-11T15:30:00Z"
#Start and duration, such as "2007-03-01T13:00:00Z/P1Y2M10DT2H30M"
#Duration and end, such as "P1Y2M10DT2H30M/2008-05-11T15:30:00Z"
#Duration only, such as "P1Y2M10DT2H30M", with additional context information

Of these, the first three require two values separated by an ''interval designator'' which is usually a solidus (more commonly referred to as a [[slash (punctuation)|forward slash]] "/"). Section 3.2.6 of ISO&nbsp;8601-1:2019 notes that "A solidus may be replaced by a double hyphen ["--"] by mutual agreement of the communicating partners", and previous versions used notations like "2000--2002".<ref>{{Cite web |title=Info on ISO 8601, the date and time representation standard |url=https://jkorpela.fi/iso8601.html |url-status=live |archive-url=https://web.archive.org/web/20171014035101/http://jkorpela.fi/iso8601.html |archive-date=2017-10-14 |access-date=2012-08-29 |publisher=Cs.tut.fi}}</ref> Use of a double hyphen instead of a solidus allows inclusion in computer [[filename]]s;<ref>{{Cite web |date=2012-01-01 |title=ISO 8601 - Getting with the Times (and Dates) |url=http://www.hydrogold.com.au/news_2012.html#iso8601 |url-status=live |archive-url=https://web.archive.org/web/20140125104222/http://hydrogold.com.au/news_2012.html#iso8601 |archive-date=2014-01-25 |access-date=2013-08-13 |publisher=Hydrogold}}</ref> in common operating systems, a solidus is a [[Filename#Reserved characters and words|reserved character]] and is not allowed in a filename.

For <start>/<end> expressions, if any elements are missing from the end value, they are assumed to be the same as for the start value including the time zone. This feature of the standard allows for concise representations of time intervals. For example, the date of a two-hour meeting including the start and finish times could be shown as "2007-12-14T13:30/15:30", where "/15:30" implies "/2007-12-14T15:30" (the same date as the start), or the beginning and end dates of a monthly billing period as "2008-02-15/03-14", where "/03-14" implies "/2008-03-14" (the same year as the start).

If greater precision is desirable to represent the time interval, then more time elements can be added to the representation. An interval denoted {{nowrap|"2007-11-13/15"}} can start at any time on {{nowrap|2007-11-13}} and end at any time on {{nowrap|2007-11-15}}, whereas {{nowrap|"2007-11-13T09:00/15T17:00"}} includes the start and end times.
To explicitly include all of the start and end dates, the interval would be represented as {{nowrap|"2007-11-13T00:00/16T00:00"}}.

===Repeating intervals===
{| class="infobox" style="text-align:center; width:23em"
|-
| Rn/<interval>
|-
| R/<interval>
|}
Repeating intervals are specified in clause "4.5 Recurring time interval". They are formed by adding "R[n]/" to the beginning of an interval expression, where ''R'' is used as the letter itself and [n] is replaced by the number of repetitions. Leaving out the value for [n] or specifying a value of -1, means an unbounded number of repetitions. A value of 0 for [n] means the interval is not repeated.

If the interval specifies the start (forms 1 and 2 above), then this is the start of the repeating interval. If the interval specifies the end but not the start (form 3 above), then this is the end of the repeating interval. For example, to repeat the interval of "P1Y2M10DT2H30M" five times starting at {{nowrap|"2008-03-01T13:00:00Z"}}, use {{nowrap|"R5/2008-03-01T13:00:00Z/P1Y2M10DT2H30M"}}.