Date Precision XMP tag

[neebah]

Other than just dumping the information in xmp-subject is there any other location that would seem appropriate for storing date precision.  Such as accurate to the nearest hour/ day/ month/  year/  decade/  etc...   

[Hayo Baan]

Instead of subject, perhaps a user defined tag would be more appropriate?

[neebah]

how does one create a beastie in exiftool

[Hayo Baan]

Sorry, should have included a link to the config file documentation.
Adding an XMP tag isn't that hard, just follow the instructions in the config file sample and you should be able to work it out. If not, post what you have come up with here and we will help you along