There is an effort to define an extension to ISO 6801 to allow approximate and/or uncertain dates to be represented. This is being led by the US Library of Congress, and is already in use at some universities.
See http://www.loc.gov/standards/datetime/ (http://www.loc.gov/standards/datetime/)
What is the chance of ExifTool supporting these date formats? Could some or all of the various "date" tags be extended to allow these values?
Note that, for myself, and I am sure others, this is not simply an academic question. E.g., when tagging scanned photographs the exact date is rarely known. It would be very useful if such a scheme where available. Of course, one could use these in XML data fields, but more "native" representations would be nice.
I don't understand the question.
ExifTool doesn't define the metadata standards, it just implements them. If any of the standards adopt the ISO 6801 extension you mention, then of course ExifTool will support this.
- Phil