I have a wall in the middle of my house which I have been told is a shear wall. The image below is a diagram I put together real quick to show what it looks like. The grey lines on the right are perpendicular exterior walls. The orange-ish section on the right is actually exterior since the foundation jogs a bit there.
It doesn't seem like the 1x6 that crosses in the middle does much. I intend to put French Doors in this wall but need to know what I'm getting myself into.
The wall runs parallel to all the joists and trusses in the house and sits directly under one truss. The far left side of the wall actually has a vent running up through it directly through the truss above. When they built the house, they cut a 12" gap in the truss, which makes me not so sure if the wall is load bearing or not.
Oh, and I live in Seattle.