Site Building
Thumbnail Index
Since Indexes are galleries, configuring them is mostly the same process but Indexes feature additional options for choosing and styling their contents.
Filtering
Sets are created through the page list. After you create a Set, it will appear in the "Filter by" menu as an option for filtering the Index.
Tags allow for more complex collections of content. You can assign tags by right-clicking a page in the page list and choosing “Settings”. A page can have any number of tags and multiple tags can be collected into one Index.
If nothing matches the Thumbnail Index’s filter, it will display three square placeholders while you are editing, to indicate the presence of a Thumbnail Index.
Thumbnail Appearance
In the settings menu for each Thumbnail Index, you can also choose to render the Title and the Tags inside the caption area of the gallery. Style them inside your CSS through .caption .page-title and .caption .tags / .caption .tags a.