Thanks Tom, at long last, an actual enlargeable photo of the product in it's packet with the description printed on it. Which confirms that the only name ESU has given it is 5. Nowhere does it say V5. As I suspected that moniker is an invented one by retailers who should know better. That it is a board replacement type, specifically made for model trains in the American & Australian markets, is a departure from the norm, certainly. L,ooks like a Loksound programmer will be an essential accessory to use them to get the sound file you require. Contradictorally it also says "unlimited variety of sounds" which gives the impression that files are already loaded. Maybe they come with Moo-Cows and Ducky-Wuckies as standard.
It seems odd, that now, most if not all US model makers are going to 21 pin motherboards in their latest releases, something that ESU pioneered, that they have released this board to suit what are now the obsolete, although numerous, models, to compete with the likes of Soundtraxx. I can understand them wanting to move away from multiple, specific sound file type decoders to a generic programmable one, using the downloadable files on their site, but why supersede the previous Loksound Select that probably could have been made that way too. Then go and change it's name as well and give it a number that was in sequence with the Euro product.
If they are that confused, it's no wonder anybody else would be too.