Best ask Lexel, I’m pretty sure it’s one of his.
If you search hard you might find an image where all (Lexel) pins are labelled. Turned around from how everyone else has been doing it for years. Simple enough to buzz it out, if you are prepared to remove the driver. But I think he would prefer to keep it a proprietary mystery, along with his derivative driver designs, and discourage others who prefer open-ness. And make proprietary programming keys that don’t fit anything else.
Though he did start openly, having been donated the idea, but that deteriorated, other, perhaps more knowledgeable people, chipped in with their own better and more flexible ideas, but were, frankly, shouted down. So we gave up. It’s not all sweetness and light here.
AFAIK TK asked Emisar to put the contacts onto the Emisar D4S. Which was great. Then a lot of bandwagon jumping went on with jockeying for position, leading, frankly, nowhere, because the most vocal also seemed to be the most dim and obstinate, and the cleverest just preferred to crack on, doing their own stuff.