Thanks :-)
Those are layer alignment targets
Those are layer alignment targets
However, I should have placed auxiliary axis points in the front copper layer to support aligment for pich and place etc. but this little project will be hand mounted so it is not needed. Further, there are no mounting holes as I would snap the PCBA in place in an encapsulation. Snap need no space for holes and spacers, and they save cost for drilling and fixing by screws. Not that cost is an issue for this project but for most mass production, cost-down is a serious task.
Well, I guess that now I know the basics and some of the pitfalls for PCB layout, next level is then to learn what is needed for mass-production ;-)