It's kind of hard to tell what's going on in this photo, but the branch with the yellow label is the grafted scion, with leaves showing on the top.
It was grafted onto the trunk directly, because the poor old tree is growing at a 45 degree angle to the ground. I am hoping to encourage this new branch to become a modified trunk, to grow in a healthier direction (up), and eventually cut back most of the rest of the tree so it doesn't have to rely on dozens of props anymore. This is a 5 year project.
Rind grafting involves making a slit in the bark that is deep enough to insert the scion, but which runs along the inner bark of the rootstock, not into the interior. The scion is cut into a chisel shape, and slid into the cut, so it's inner bark will connect with the rootstock inner bark. It is very strongly attached this way, so it does not need support to stand upright. It should be sealed with grafting wax to keep the cut surfaces from drying out.