To tag an asset with a filter, go to “Setup” > “Asset Management” > “Templates”.
Use the button in the upper right-hand corner of the menu to put your gallery into "list" view. Next, select the assets that you want to tag.
Click on the vertical ellipses in the upper right-hand corner of the menu and then select “Attributes”.
Type in the filter or filters that you wish to add, and then click “Save” and “Close”.