This stop bladed scarf joint with cogs takes a bit more work to cut than a simple bladed scarf joint. But the cogs (the projections into the tenon that form a t-shape) added to the stub tenons help lock the joint in place. They also increase the bending strength of this joint against horizontal loads.
Like all other scarf joints, you can use this joint to create a longer beam out of two shorter members. And it will be further secured with pegs or structural screws.
Bladed half-lap scarfs tend to cause splitting of the timbers when loaded in strong axis bending as seen in the image below. Special thanks to Jim DeStefano from DeStefano & Chamberlain, Inc. for the image and the warning.