Exiv2

Hello.

I've got a larger number of images which have a XMP:Subject tag, which I can't seem to be able to remove…

exiftool (and also Flickr ) are able to read this XMP:Subject tag - search for "April", in exiftool it's shown at the end in the [XMP] Subject line and Flickr automatically imported it as a tag "April, Mai, Juni" (which is correct, since "April, Mai, Juni" is one tag).

I'm now looking for a way to automatically remove this XMP:Subject tag from all image files I've got. So I tried:

MacBook-Pro:Unsortiert alex$ exiv2 -v -M"del Xmp.dc.subject " 18.jpg 
Datei 1/1: 18.jpg
Löschen Xmp.dc.subject
MacBook-Pro:Unsortiert alex$ exiftool -q -q -H -G -U -a 18.jpg | grep -i subject
[XMP]                - Subject                         : Hato Caves, Flitterwochen, Curaçao, Web, 2003, April, Mai, Juni,  

The field wasn't removed; but generally, it seems to work.

MacBook-Pro:Unsortiert alex$ exiv2 -v -M"set Xmp.dc.subject Palmtree" 18.jpg ; exiftool -q -q -H -G -U -a 18.jpg | grep -i subject ; \
 exiv2 -v -M"del Xmp.dc.subject " 18.jpg ; exiftool -q -q -H -G -U -a 18.jpg | grep -i subject
Datei 1/1: 18.jpg
Setzen Xmp.dc.subject "Palmtree" (XmpBag)
[XMP]                - Subject                         : Palmtree
[XMP]                - Subject                         : Hato Caves, Flitterwochen, Curaçao, Web, 2003, April, Mai, Juni,  
Datei 1/1: 18.jpg
Löschen Xmp.dc.subject
[XMP]                - Subject                         : Hato Caves, Flitterwochen, Curaçao, Web, 2003, April, Mai, Juni,  

This shows, that I was able to add another entry in the Subject array ("Palmtree") and exiftool showed that just fine; I was also able to remove it and this was confirmed by exiftool.

I've asked this on the Exiftool forum as well, and Phil replied that this is because of a non-standard header.

Is this the same reason, why exiv2 v0.20 also cannot remove this Xmp.dc.subject field?

Thanks,
Alexander