In this image, Ix is up and Iy is to the right (centroid coordinate on the highlighted area).

The highlighted section is long and uniform, but in this image it appears flat. It is also the region I want to calculate stress in, let's say in the top of the highlighted region.

Stress = Mc/I, where c is the vertical distance from the centroid to the location of interest and I would be the horizontal moment of inertia through the centroid.

From the table below, I assume that Iy is the horizontal moment of inertia through the centroid. Is this true?

It is interesting that Lzz is equal to Iy.

What do the 9-moments of inertia denoted Lxx through Lzz refer to, since they are being calculated at the centroid?