Ah sorry, I thought I had written ballast of the current form. That was my intention, but I failed to type what I had thought. Otherwise there wouldn't be a po

Ah sorry, I thought I had written ballast of the current form. That was my intention, but I failed to type what I had thought. Otherwise there wouldn't be a point to mention that 50 years ago other, less stable ballast was still in use in some places.