Dan, The Library of congress standard is 0.092 inches center to center between dots in cells, twice that between cells and as you said vertically between lines.
I think dot diameter is 0.020 and height is 0.015 inches of course. Some idiot decided the california standard should be based on 0.1 inches between centers etc. I won't give his name but he works next door to me. If doing mechanically raised dots, it appears to take about an ounce of vertical pressure to keep them up shal we say. tom Fowle
