multiplex fiction is a science-fiction magazine in the literal sense, published or not. If you ever got lost in a Multiplex while looking for the right movie – that’s it: Bigger inside that outside.
Height, width, breadth, and a couple of other things.
Besides time machines and higher dimensions, the editors have a distinct quirk for shape-shifting. Hence, representative definitions such as “editor” or “published by” only make sense as ephemeral gimmicks.