Once you’ve created some tags and set them up the way you want, it’s easy to use them in another library. Assign the tags to a file, and then drag it into the other library. EagleFiler will transfer the tags (along with their abbreviations, colors, and hierarchy) to the other library. This is really just a special case of a general EagleFiler feature that metadata (tags, notes, titles, etc.) are preserved when copying files between libraries.