I tried using hierarchical keywords in Bridge. I had been redoing my file structure and got it to where I wanted it and I was experimented with bringing the photos into Lightroom. The keywords were a real mess in LR. I decided a non-hierarchical system was not so bad and that I didn't need so many - I wanted to undo what I had. I imported the files into IV and created catalog sets to mirror my most important keywords. I used File Info in Bridge to remove all the keywords and then used IV to sync the simplified keywords back into the files.
I worked well to a point but there were some persistent hierarchical keywords that kept popping up in Bridge and I couldn't delete them. And even more would show up when importing into LR. I think I have tracked this down to these sample lines in the XML sidecar files:
xmlns:lr="
http://ns.adobe.com/lightroom/1.0/">
  <lr:hierarchicalSubject>
  <rdf:Bag>
   <rdf:li>People|People-Work</rdf:li>
   <rdf:li>Ratings|2Star|MP: 2Star</rdf:li>
   <rdf:li>Ratings|1Star|MP: 1Star</rdf:li>
  </rdf:Bag>
  </lr:hierarchicalSubject>
Is there a way to automate going through the sidecar files and removing every line between <rdf:Bag>... <rdf:Bag> ? The funny thing is I don't remember importing the originals of these files into LR, so I am not sure how these lines got in the file.
Mark