New to Omeka but wanted to share a small tip that maybe useful for others.
I was looking for a way to have a predefined list of tags not yet related to a specific item so that contributors could choose from available tag options (something like a dropdown menu) when creating new items but i couldn’t find a plugin that does that. Though, I noticed that on the tag field if you start typing some letters Omeka suggests from existing tags so, I added an empty item that I use to create new “predefined” tags and they as expected end up on the tag explorer. Then you can delete the empty item and tags will remain on the tag explorer for use even if they are still not applied to a real item.