Extended Date Time Format
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EDTF - The Extended Date/Time Format - defines features to be supported in a date/time string, features considered useful for a wide variety of applications

Basic date and time formats are specified in ISO 8601-2004, the International Standard for the representation of dates and times. ISO 8601-2004 is not sufficiently expressive to support various semantic qualifiers and concepts than many applications find useful. For example, although it can express the concept "the year 1984", it cannot express "approximately the year 1984", or "we think the year is 1984 but we're not certain". These as well as various other concepts are therefore often represented using ad hoc conventions; EDTF provides a standard syntax for their representation. Further, 8601 is a complex specification describing a large number of date/time formats, in many cases providing multiple options for a given format. Thus a second aim of EDTF is to restrict the supported formats to a smaller set.

EDTF was developed over the course of several years by a community of interested parties, via a listserv, which is still in operation; join the discussion. A Draft Specification was published in 2012. A number of implementers have developed prototype implementations.

EDTF functionality has been integrated into a draft revision of ISO 8601 to be published in mid 2019.

The draft specification has therefore been superseded and a revised EDTF Specification is now available.

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