Directory · 21 entries
Date precision and uncertainty notation
This table lists notations and terms used to record how precise or how certain a date or time is. Each row gives the meaning and the standard that defines it. The Extended Date/Time Format from the Library of Congress covers approximate and uncertain dates 1. RFC 3339 covers exact Internet timestamps with UTC offsets 2. RFC 3161 covers trusted time-stamp tokens 3, and NIST SP 800-86 describes file times used as evidence 4.
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? (question mark)
- Meaning
- The value is uncertain 1
- Standard
- EDTF
~ (tilde)
- Meaning
- The value is approximate. 2004-06~ is June 2004, approximate 1
- Standard
- EDTF
% (percent)
- Meaning
- Uncertain and approximate. 2004-06-11% applies to the whole date 1
- Standard
- EDTF
X (unspecified digit)
- Meaning
- Replaces one or more rightmost digits at Level 1, or any digit in a component at Level 2 1
- Standard
- EDTF
.. (double dot)
- Meaning
- Open start or end of an interval. 1985-04-12/.. has an open end 1
- Standard
- EDTF
Null start or end
- Meaning
- A start or end date that is unknown 1
- Standard
- EDTF
21 to 24 in the month place
- Meaning
- Spring, Summer, Autumn, Winter. 2001-21 is Spring 2001 1
- Standard
- EDTF
Y prefix
- Meaning
- A year of more than four digits, as in Y170000002 1
- Standard
- EDTF
S (significant digits)
- Meaning
- 1950S2 is a year from 1900 to 1999, estimated 1950 1
- Standard
- EDTF
[ ] square brackets
- Meaning
- One member of the list applies 1
- Standard
- EDTF
{ } curly brackets
- Meaning
- All members of the list apply 1
- Standard
- EDTF
Z
- Meaning
- Suffix for a UTC offset of 00:00 2
- Standard
- RFC 3339
-00:00
- Meaning
- UTC time known, local offset unknown 2
- Standard
- RFC 3339
+hh:mm or -hh:mm offset
- Meaning
- Local time offset from UTC. 1996-12-19T16:39:57-08:00 equals 1996-12-20T00:39:57Z 2
- Standard
- RFC 3339
Seconds value 60
- Meaning
- Leap second at the end of a month where one occurs, as in 1990-12-31T23:59:60Z 2
- Standard
- RFC 3339
Fractional seconds
- Meaning
- Parts of a second, as in 1985-04-12T23:20:50.52Z 2
- Standard
- RFC 3339
genTime
- Meaning
- Time a time-stamp token was created, in UTC 3
- Standard
- RFC 3161
accuracy
- Meaning
- Margin around genTime giving upper and lower bounds 3
- Standard
- RFC 3161
Modification time
- Meaning
- Last time a file was changed in any way 4
- Standard
- NIST SP 800-86
Access time
- Meaning
- Last time any access was performed on a file 4
- Standard
- NIST SP 800-86
Creation time
- Meaning
- Time the file was created. Becomes the copy time when a file is copied to a system 4
- Standard
- NIST SP 800-86
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Notes
- EDTF Levels 1 and 2 specify features described in ISO 8601-2, according to the Library of Congress 1.
Rules and charges change. Check the official source linked on this page before you pay or travel. Spotted an error? Email hello@sequenceofrecord.com.
Sources
- Library of Congress: Extended Date Time Format (EDTF) Specification (4 February 2019)
- IETF: RFC 3339, Date and Time on the Internet: Timestamps (July 2002)
- IETF: RFC 3161, Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP) (August 2001)
- NIST: Special Publication 800-86, Guide to Integrating Forensic Techniques into Incident Response (August 2006)