Here is another visualization and examples of the corner relative system that I proposed:
If one dislikes using Latin characters, using the Chinese characters is another option:
I like how the “simple coordinates” is both corner-relative and only use numbers, but I don’t like how they use apostrophes to disambiguate which corner.
Another variation (which would be convenient for pen and paper) is to draw lines around the number to indicate the closest corner or edge. Here is an example:
For positions on the “tenth line” or “tengen”, one could also use special symbols, for example:
