User blog comment:Neowitch/Character Table Guide/@comment-972068-20130426145705/@comment-972068-20130426152403

It uses the thing. Basically, it allows you to stack multiple gallery templates on top of one another. Another example is Template:Marine Members Gallery. The Canon Marines and the Filler Marines or different templates. This is because the Canon Marine template has the option to "multi" on the bottom, and the filler Marine template has the option to "multi" on the top. Without the "multi", it looks like two gallery templates on top of each other. But with the "multi", it's like a different section.

I'm probably super vague and not explaining this very well, but just view Template:Filler Marine Members and you might see what I mean.