How do I use 'sections' with procedural meshes?

Hello,

I am exploring using ProceduralMesh to build 3D text models out of individual static mesh letters and thought I could merge them using ProceduralMesh.
I figured one could use the ‘section index’ bit to add each letter to. Even if I am not 100% sure what the 'section’s really are.

(I tried just appending the input arrays and build the procedural once, but the second mesh then looks mangled)

Would someone be able to tell me why this is not generating a procedural mesh showing both the two input meshes?

EDIT: Oh wait! I just figured it out! I just need to use Section Index 0 for the second input mesh, but use index 1 when I am merging that in. As the input mesh is just one section, I suppose. That works though.

Cheers,