Editing ISO 8601 (section)

== Standardised extensions==
ISO&nbsp;8601-2:2019 defines a set of standardised extensions to the ISO&nbsp;8601 date and time formats.

; {{anchor|EDTF}} Extended Date/Time Format (EDTF)
: The EDTF is given as an example of a profile of ISO&nbsp;8601. Some of its features are:<ref name="EDTF_2019_Spec" />
:* [[Uncertainty|Uncertain]] and approximate qualifiers, '?' and '~', as well as their combined used, '%'; they can be applied to the whole date or to individual components.
:* Time intervals with an open (unbounded) end or an unknown end.
:* Exponential and significant figure notation in years.
:* Special "month" values indicating sub-year groupings such as seasons and quarters.
:* Syntax for serializing a list of dates.
: The EDTF features are described in the "Date and Time Extensions" section of ISO&nbsp;8601-2:2019

; Repeat rules for recurring time intervals
: ISO&nbsp;8601-2:2019 also defines a format to constrain repeating intervals based on syntax from [[iCalendar]].<!-- We can use an example here. Maybe a rule for Easter day? -->