Editing Timestamp (section)

==Digital timestamps==
{{main|Timestamping (computing)}}

This data is usually presented in a consistent format, allowing for easy comparison of two different records and tracking progress over time; the practice of recording timestamps in a consistent manner along with the actual data is called [[timestamping (computing)|''timestamping'']].<ref name="Medeiros2009">{{cite book|author=Claudia Maria Bauzer Medeiros|title=ADVANCED GEOGRAPHIC INFORMATION SYSTEMS -Volume I|url=https://books.google.com/books?id=kBnFDAAAQBAJ&pg=PA59|date=19 September 2009|publisher=EOLSS Publications|isbn=978-1-905839-91-9|pages=59}}</ref>

Timestamps are typically used for [[Data logging|logging events]] or in a [[sequence of events]] (SOE), in which case each event in the log or SOE is marked with a timestamp.

Practically all computer file systems store one or more timestamps in the [[file system#Metadata|per-file metadata]].
In particular, most modern operating systems support the POSIX [[stat (system call)]], so each file has three timestamps associated with it:
time of last access (atime: <code>ls -lu</code>),
time of last modification (mtime: <code>ls -l</code>), and
time of last status change (ctime: <code>ls -lc</code>).

Some [[file archiver]]s and some [[comparison of version control software|version control software]], when they copy a file from some remote computer to the local computer, adjust the timestamps of the local file to show the date/time in the past when that file was created or modified on that remote computer, rather than the date/time when that file was copied to the local computer.

Timestamps are often found to be dirty in many cases. Without cleaning up inaccurate timestamps, time-related applications such as provenance analysis or pattern queries are not reliable. To evaluate the correctness of timestamps, temporal constraints can be applied, declaring distance limits between timestamps.<ref>{{Cite journal |last1=Song |first1=Shaoxu |last2=Huang |first2=Ruihong |last3=Cao |first3=Yue |last4=Wang |first4=Jianmin |date=May 2021 |title=Cleaning timestamps with temporal constraints |url=https://link.springer.com/10.1007/s00778-020-00641-6 |journal=The VLDB Journal |language=en |volume=30 |issue=3 |pages=425–446 |doi=10.1007/s00778-020-00641-6 |s2cid=7559769 |issn=1066-8888|url-access=subscription }}</ref>