Well excuse the F out of me Jr.
I'm in the USA, and as far as towing mirrors go, on almost 20 year old trucks, I would be willing to wager that there are more aftermarket mirrors out there than there are OEM at this point, especially considering they span over 8' wide when deployed and are usually the first thing to go in an impromptu tight quarters situation. As far as my service manual, I didn't check it out from the service department at my local stealership, however I seriously doubt in any version of service manual (save for a Haynes, where they disassemble a vehicle and document it themselves) aftermarket non OEM, serves no function, pointless aesthetic design choices of ANY part would be incorporated into such a document, if they cared at all about being taken seriously that is. Ever seen a service manual with aftermarket door edge guards in it, or curb feelers? What country are you in where you think jumping down someone's throat and insulting them is acceptable behavior? This is a forum, by definition, a place to engage in discussion and share ideas and thoughts. Your lack of any relevant thought, or anything worth contributing has been noted. So go read up on YOUR factory service manual, and back up your **** instead of just blindly staring ****.
As far as it goes, only evidence of their existence has been shown and proven.
Could have shown a pic of a mirror without it to demonstrate your superior intellect and still oem selection of parts. But ya didn't.
And yeah, my factory service manual, factory parts manual, parts drawing at the dealership, ALL show the mystery pocket, only on one mirror. And it's not referenced anywhere. So..