This year I am exploring Wing Chun, looking for techniques that I might recognize from my Shotokan katas. I've found one.
Wing Chun has the concept of a "stop kick," which is somewhat alien to anything we do in Shotokan. As the opponent advances, you place your foot on his thigh and press it away. This straightens his knee and utterly stops him in his tracks. The motion reminds me of pressing the brake pedal on a car.
In the demonstration I viewed, the kick was accompanied by a backfist gesture at shoulder level. This was used to deflect a descending hand attack, as in deflecting a downward sword cut by batting the hands to the side.
The sifu then set his foot down and closed the distance to the knees-and-elbows range that Wing Chun prefers.
Shotokan's heian nidan has this gesture at step 7, except for the substitution of the side-snap kick, which is a well-known shotoism. All other pinan shodan (heian nidan) performers use a front snap kick there. The gesture they use is exactly what we see in the Wing Chun stop kick.
So I regretfully conclude that I mis-interpreted that move in my book, but note that this new application is a much better fit to the kata than the one I had before. It just keeps getting better and better.
I am going to spend more time with Wing Chun.