Since when has anyone ever tried to pronounce 'GPS' as anything other than G-P-S? Also "ECS" = "Ecosystem"? Maybe I'm just crazy but I've never heard or read anyone abbreviate ecosystem as 'ECS'. I've come across ECS as entity component system in video game engines, but never as just 'ecosystem'. Also it's defined exactly once in chapter 5 and then never used again in the book. Why even bother to mention it then?
Oh and publish it as a PDF, but then have no actual page numbers?