Bookmark Tagging

When I save a web browser or e-doc reader bookmark with a tag, the logic should be simple in this one respect.

If I am tagging into a "Nihongo" folder in which the only tag beginning with 'd' is "dictionary", then typing 'd' should bring up that tag at the top of the list and not 'Darfur' from my 'Geo" or "International Relations" folder.

Surely someone working with tagging for semweb app's will get this simple logic in place.

In truth, the suggested tag that I receive in Firefox is "dARPA" for the tag "DARPA". Yet nothing in the "Nihongo" folder or it subfolders is tagged "DARPA".