Anteprologue to "To Rule the Skies‪"‬

A prologue comes before the formal chapters of a novel, and generally sets a scene, introduces some important characters, or reveals a theme whose importance will become apparent later in the story. My novel "To Rule the Skies" already has a prologue, but this story takes place chronologically immediately before that prologue, so I'm inventing a term for it--the "Anteprologue". Think of it in the same vein as the Doctor Who webisodes between seasons or the Marvel One-Shots that give more background to various characters in the Marvel Universe.