I just got the email. Instead of (better than) the CCF it had a garbled (by his email program because it was too long) copy of a URL, back to RC. So I found the right CCF at
[Link: remotecentral.com]

which I had already downloaded and examined (as I have the majority of CCFs from RC).

It uses RECS80 protocol with the format of Pronto Hex that gets the toggle bit right, which prevents it from being used multiple times in a sequence for purposes of extending it.

If I'm on the right button in the CCF, the current Pronto Hex is
7000 006d 0000 0008 0011 000d 0010 0002 0017 0002 0002 0002 0003 0002 0002 0003 0002 0003 0000 011b

Later I'll use MakeHex to make a raw version, which ought to solve the problem.