Some other comments¹ have said that some Selectrics had a half-space control, so that would provide 1/24″ horizontally. I think that's the finest in the paper,

Some other comments¹ have said that some Selectrics had a half-space control, so that would provide 1/24″ horizontally. I think that's the finest in the paper, unless I've missed a case. ¹ e.g. https://news.ycombinator.com/item?id=35177786 https://news.ycombinator.com/item?id=35177786