I’ve tried searching online, but could not find information on that topic.
I’m trying to understand how tags are handled in DEVONthink:
I see some tags in the Inbox folder; these tags are also present in the tags list of another database.
The tags in the inbox are empty. Where the same tags in another database do show me items, when I click the tag.
Q1: why some tags are duplicated in the inbox…?
Q2: and why if I select the tag in the inbox it does not show me anything. where if I select the same tag in another db, it returns me all the items with that tag…?
From my observations, what @chrillek says is correct. If you don’t want a build up of empty tags, you can create a smart rule to delete empty tags that runs (for example) every time you start DT.
Correct. Tags belong to a database and can logically have duplicates. This is no different than the index in two books on similar topics. They don’t share one index. Each has their own and if you close one, you still have its index. Simple
PS: Read the Getting Started chapter of the built-in Help and manual.