What do with the date of historical images, even before Christ?

[sinus]

Well, it's Pentecost and my question might fit in because it's a historical holiday.

I have a question, where IMatch cannot do anything, I think, this is a general problem, but there are some genealogy experts here on the forum who might have some kind of a solution or ideas.

That automatically means that people who deal with history usually use special software, I know of course.
But that's not what I want, I want to use IMatch. 
And if there is no solution, well, then I will find some "trick solution" that will do for me.

My question now:
What do I do if I have pictures that show something that took place e.g. 20 years after Christ or pictures that show 5000 before Christ (Egyptians etc.), what do I do with the date?
Is it possible to enter them in a way that they will be displayed that way?

I have seen that if I use the field
{File.MD.XMP::photoshop\DateCreated\DateCreated\0}
and fill it in with

0100:06:05 13:07:48
for 100 years after Christ, then it works and is even displayed correctly with VarToy and
{File.DateTime|format:YYYY-MM-DD hh:mm:ss}

(even timediff works)

But it no longer works if it is 99 years after Christ and further back.
Does anyone have any ideas?

If nobody has an idea, then I will e.g. find another field for that and will think about the best way to overcome this.

I did search here for uncertain dates, historica and genealogy but without a clue.

[Mario]

As per Microsoft documentation, most of the date/time code IMatch uses handles dates betwen January 1, 100, through December 31, 9999.
Not sure if all affected controls, ExifTool, 3rd party libraries and toolkits, apps, the date & time routines apps use etc. deal with such dates. Or
I don't test this, because it is extreme. Most computers don't know that dates before 1970 even exist.

I would recommend to not use IMatch date & time tags (XMP tags) to store historical dates before 1700, to be on the safe side. This should work.
If you need to date pre-roman files or even older, probably using a text field is best.

[sinus]

Thanks, Mario
Very good. And IMatch does it well, because  the date January 1, 100 is exactly, what does still work, like you wrote.

I think, I will do, what you recommended, to be safe.
But it is really asthonishing, how precise IMatch works also with extreme dates.

Very cool. 

[sinus]

...
I would recommend to not use IMatch date & time tags (XMP tags) to store historical dates before 1700, to be on the safe side. This should work.
If you need to date pre-roman files or even older, probably using a text field is best.

Just a short update:
After my personal, not experienced tries, you, Mario, are correct with 1700.
1700 should be safe.

In my tries, I found out, that the border for safe dates is the year 1601.
1601 works but 1600 and even more back works not more.

This means, that the 1700, what Mario wrotes, should be really safe.
Maybe it is also safe until 1601 back, but for sure you will get problems, if you do write dates from year 1600 and earlier.

For me this is good to know. Just if someone is interested. 

[DigPeter]

Surely date created refers to when the image was made?  Date of the subject - 3000BCE for instance for Stonehenge - should put into a different tag - e.g. 'Subject date'?

[jmsantos]

I think the best location for that date data would be Artwork or Object, Circa date created. IPTC Standard XMP Extension Iptc4xmpExt:AOCircaDateCreated.

[Aubrey]

As per Microsoft documentation, most of the date/time code IMatch uses handles dates betwen January 1, 100, through December 31, 9999.

I wonder how Microsoft handles the switch from Julian to Gregorian calendar. I think different parts of Europe switched at different years.... and some (Greek, Russian Orthodox) have yet to change.

Aubrey

[sinus]

Thanks for your ideas.
What I wanted to know and work with, was a normal date-field, with what I can do some math like timediff or duration.

And as far as I see, this can be done until 100AD.
But some date-fields has troubles with it.

And there is the border for me 1601AD.
Mario wrote 1700AD, this is for sure safe.

Hence I will work until year 1601, all dates before I will use some other fields, like some of you wrote. But I have to check this first and to be honest, I am sure, I will find several fields, what could be used.
Ah, and yes, Stonehenge I have almost forgot, I will add it. 

BTW, I want do this for my "privat timeline". Not really important, but nice to see it can be done inside IMatch and use it, e.g. with Design&Print.