What does horizontal segmentation mean in this paragraph?

So that's number one thing that Howard did. Number two thing that Howard did is he made us realize. it's another very critical point, he made us realize the importance of what he likes to call "horizontal segmentation." Why is this critical? Because this is the way the food industry thought before Howard. What were they obsessed with in the early 80s? They were obsessed with mustard. In particular, they were obsessed with the story of Grey Poupon. Used to be, there were two mustards: French's and Gulden's. What were they? Yellow mustard. What's in it? Yellow mustard seeds, turmeric, and paprika. That was mustard. Grey Poupon came along, with a Dijon. Right? Much more volatile brown mustard seed, some white wine, a nose hit, much more delicate aromatics. And what do they do? They put it in a little tiny glass jar, with a wonderful enameled label on it, made it look French, even though it's made in Oxnard, California.