metadata - Is "Date Taken" Exif data possible on .PNG file, and is it possible to copy "Date Modified" to "Date Taken"?

I want to change the Exif data for some .PNG files so that they have the "Date Taken" tag. Is it possible to use that tag on .PNG files?

Is it possible to copy the "Date Modified" date to the "Date Taken" date for then same .PNG file? I'm using ExifTool and I've read in this question that the copying part is possible via exiftool -v "-FileModifyDate>DateTimeOriginal" * but I can't figure out how to use it on the .PNG file.

My questions:

1. Is it possible to use then "Date Taken" Exif tag on .PNG files?

2.If it is possible, how can I use ExifTool to copy the "Date Modified" tag to the "Date Taken" tag?

Answer

What Windows displays under the "Date Taken" property isn't an embedded tag. It fills that property from a number of tags depending upon the file type. For example, for a JPG, Windows will use any of these tags: EXIF:DateTimeOriginal, XMP:DateTimeOriginal, EXIF:CreateDate, and the system FileCreateDate.

ExifTool can create an EXIF:DateTimeOriginal tag in a PNG for you, but Windows doesn't support reading EXIF data in PNGs. Most software doesn't as the EXIF standard in PNG files is only a few years old.

It looks like the tag you want to use is PNG:CreationTime. That shows up in Windows as the "Date Taken" property for me (Win 8.1). So your command would be:
ExifTool "-PNG:CreationTime