Hello everyone, I was interested in knowing the purpose of notches inside a frame. It cannot be for aesthetic purposes as it's hidden inside the frame. You might think that it's there for stress release or for being more flexible but that won't explain the midway notches, only the top and bottom inside the cavity. I guess that the purpose is merely because the machinery used for manufacturing them has this requirement. So if you can enlighten me it will be amazing. Here you have the source, it's a solar panel frame (https://autosolar.es/pdf/CSUN-310-72P_ENG.pdf). Thanks in advance.