This is defintely some kind of "mode 6" (vs. regular RC6, which is mode 0). I don't know what Philips means by "6a". It's encouraging that 6a has an extra field because this RC6-6-32 does have an extra field vs. normal RC6. But I wouldn't know what to put in those three fields to try to duplicate these signals. I don't own any model of Pronto. Do you or someone else in this thread have two Prontos or a Pronto plus some other IR learning device?

Assuming no other expert jumps in with an explanation of mode 6a, it would be nice to enter a few mode 6a signals into a Pronto with different customer code, system and command numbers and then learn them to another remote and decode the results and see if they are RC6-6-32 and if so, then which field is which.

Also I'm worried because this protocol toggles the wrong bit. I wouldn't expect Philips to toggle the wrong bit, so even if mode 6a were RC6-6-32, it still probably won't work.

I just suddenly remembered something from the last time this came up, which is that it was a Microsoft product in which the wrong bit of RC6 was toggled (as you'd expect) but someone in that thread had a plausible sounding claim that it wasn't actually Microsoft's fault that the wrong bit was toggled.