XnView Software

When using categories, and "Settings, Metadata, Export Db Categories to XMP keywords" , XnViewMP can create/update XMP-lr:HierachicalSubject
OK

- Some users are using Microsoft hierarchical keywords, or Digikam hierarchical keywords
XMP:LastKeywordXMP
XMP-digikam:TagsList

So, you could add these checkboxes in "Settings, Metadata" :
- create IPTC flat Keywords (IPTC:Keywords)
- create XMP DC flat keywords (XMP-dc:Subject)
- Create XMP LR Hierarchical (XMP-lr:HierachicalSubject)
- Create XMP Digikam Hierachical (XMP-digikam:TagsList)
- Create XMP Microsoft Hierarchical (XMP:LastKeywordXMP)

I think these hierarchical keywords work exactly on the same shema as LightRoom keywords, maybe the same code can be used in each family ?

( it's not for me, I'm not using these keywords ...)

I found just recently that I have how some images tagged with Microsoft and Digikam keywords and I'd like to remove them as I will prob never use s/w using these to process my images again.