Separators are a special form of collections which are used similar to index cards in a library, they help to "split up" collections by identifying categories (such as "Studio Collections" and "Holiday Collections").
These are empty collections which do not contain any movies/shows themselves, but highlight that the collections which follow it are of a certain category.
Plex does not support creating these empty collections natively through its UI, so they can behave strangely in some cases, primarily related to showing/hiding them in the main library view. As a workaround, you can use a `placeholder_` [template variable](#shared-separator-variables) to specify a single movie/show to add to these collections so they have one thing in them and will then behave as expected. For example, `placeholder_imdb_id: tt0068646` will place The Godfather inside the separator in a movie library.
Note that the `template_variables:` section only needs to be used if you do want to actually change how the defaults work. Any value not specified is its default value if it has one if not it's just ignored.