[digiKam-users] digiKam "date"s and times

[Jim Todt]

Hi.  digiKam newbie here.  Please bear with me as this may get a little 
long...

I've started testing digiKam (6.1), looked at settings, looked at the 
website, docs, Nabble forum, & even tried reading some code.  But I 
haven't found the specifics I'm looking for... (Hopefully they're in a 
spec document or user document somewhere, and not just in the code...)

digiKam makes reference to "date" often; and in one place in the docs it 
talks about "EXIF date" as being the 1st choice.  But even within EXIF 
there isn't just 1 "date"...  So what does "date" really mean?  digiKam 
seems to use "date" in at least 3 places:

1) Importing.  Which drives Properties & Metadata.  I seem to get these 
results:

1a) Properties->Photograph Properties->Created comes from 
EXIF-Spec:DateTime.  What ExifTool calls ModifyDate.  The last time the 
picture was modified (not created).

1b) Metadata->EXIF->Image Information->Date and Time also comes from 
EXIF-Spec:DateTime.

1c) Metadata->EXIF->Photograph Information->Date and Time (Digitized) 
comes from EXIF-Spec:DateTimeDigitized.  The time that the image was 
first digitized.

1d) Metadata->EXIF->Photograph Information->Date and Time (Original) 
comes from EXIF-Spec:DateTimeOriginal.  The "taken" time - when the 
camera shutter was actuated.

2) View menu sorting.  This seems to use the filesystem dates.

3) Left side Dates & Timeline.  These seem to use either the Created or 
the Date and Time above - in either case ultimately EXIF-Spec:DateTime.

Hopefully someone(s) can help with these questions:

a) Is the above correct as to what dates digiKam is using for what purposes?

b) In a recent forum thread there was talk of a date needing to appear 
multiple times before it's used - is this correct?  If so, what is the 
reason for this rather than using each date per the spec?

c) Why isn't the Original date used for sorting, selecting, etc.? As the 
"taken" date, this would seem to be the most appropriate choice rather 
than a date which can be changed later by other software...

d) I think in the same forum thread there was talk of a coming ability 
for the user to specify what datetime fields should be selected in what 
order to be used for each purpose?  Is that correct?  If so, is there a 
timeframe for when this might be implemented?

e) The latest EXIF spec includes Offset fields to (finally) include 
Timezone.  However, digiKam only lists 1 of the 3 EXIF Offset fields.  
Is this a work in progress?  Will digiKam include the other 2 (when?) 
and use these Offset fields to correctly sequence pictures from multiple 
Timezones?

f) Is there a Best Practice for when & how to use UTC time in digiKam?

g) Or is there some other Best Practice for how dates and times and the 
related fields should be handled in digiKam?

Thanks for your help!