The extension value in Cycles IMageTexture node is doing exactly what it's supposed to. LaFemm's UV's extend across several UV spaces, "Tiled UVS". That's what the extension value does. It controls how the image is mapped across multiple UV spaces.

The Cycles documentation covers this better than the Poser manual. https://docs.blender.org/manual/en/latest/render/shader_nodes/textures/image.html