[brianmwaters_hn]

It's called an "autoblock" by climbers today in the US: https://en.wikipedia.org/wiki/Autoblock

[glomph]

That appears to be a slightly different knot. The final stage where the bottom loop goes through the top isn't done for an autoblock.

[masklinn]

> The final stage where the bottom loop goes through the top isn't done for an autoblock.

That'd be the french knot which only blocks in one direction. The Machard knot which blocks in both directions does not loop through itself, the karabiner goes through both loops to close the knot.