SUMMARY

Set date for analog photos with unknown or partial unknown date (and unknown time). 

In my collection, I have many analog photos I have digitized. 
Generally, I have no idea of correct time for when the photo was taken. 
In many cases I do not know the year.
In some cases I know the year.
In some cases I know the year and month.
In some cases I know the year, month and date. 

I have used Photoshop Element Organizer (PSE14). In PSE14 I could change the date to eg totally unknown - date is shown as ”?”. I could also change to only year etc. Photos placed accordingly in the time line. 

As far as I can find out I can only set a complete date (and time also included) in digiKam. 

My wish is a possibility to manage incomplete date information in digiKam, including photos shows up correctly in eg Date and Time line views and works in Search.

This wish is open to how it is best implemented but if it can be within standards it is an advantage. Info below under Additional information from standards is only for information.  


SOFTWARE/OS VERSIONS
Windows: 
macOS: 12.6
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

I have done a bit of testing to find out how PSE14 handle, but so far I cannot conclude if PSE export this to file (it affect metadata but I have not concluded if details are transferred) or handled only in its database. If requested, I can do some more research how it is handled in PSE14.

I have done some reading of EXIF, IPTC and XMP standards and found some information that may be useful. Below are extracted text from some interesting paragraphs. I am not expert to understand them, but to me it indicates as something like I want maybe can be done within the standards. 

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IPTC Photo Metadata Standard 2021.1

6.10 Date Created (page 22)
Designates the date and optionally the time the content of the image was created rather than the date of the creation of the digital representation.
Note 2: Software showing the metadata user interface should adopt a widget for this property that supports editing truncated dates, like year and month only, or year only. Software embedding truncated dates as IIM DataSet 2:55 should use the value "00" for undefined days or months (like "19180000" for an image taken "in the year 1918")

XMP Specs: photoshop:DateCreated [Date <External>]

Generic Implementation Notes (page 110)
13.2. Date value type
Applies to an XMP property if its value type is date: The XMP specification defines a quite flexible format for this value type, all these sets of year, month, day and time values are supported:
!"YYYY
!"YYYY-MM
!"YYYY-MM-DD !"YYYY-MM-DDThh:mmTZD !"YYYY-MM-DDThh:mm:ssTZD !"YYYY-MM-DDThh:mm:ss.sTZD
IPTC encourages makers of software to adopt a user interface widget for the Date value type properties which allows a user to enter all these variants of date and time.
Note the format of dates and times shown above is based on the ISO 8601 standard for date and time formats [ISO-8601]
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Adobe XMP Specification Part 3 Jan 2020
Table 37 — IPTC data sets of use as XMP metadata (Continued) (page 70)
2:55
2:55 0x0237 Date Created 8 ASCII digits as CCYYMMDD, 00 for unknown parts
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DC-101-2020_E Exif 2.32 metadata for XMP
A.2.2.2 Date (page 24)
Date is a date-time-value, which is represented using a subset of Date and Time Formats formatting: 
YYYY
YYYY-MM
YYYY-MM-DD
etc.
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Digikam users mail:
https://mail.kde.org/pipermail/digikam-users/2022-October/034134.html
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