Relative coordinates (https://senseis.xmp.net/?Coordinates) are infinitely scalable. The symmetries of the goban are integral to this coordinate system; it may be perfect for developing go engines. However I guess that current code might have to be completely re-written to take advantage of that. All points on the goban may be written in the form ij, ij*, i*j, i*j*, ji, ji*, j*i, & j*i* (summarised as i^j^ & j^i^). This illustrates how all points described with identical numerals (that is all variants of i^j^& j^i^) are in the same position relative to their corner, taking all symmetries into account (including those across the goban's two main diagonals.)lightvector wrote: The only way to get around the 25x25 restriction for a particular GUI program or match-playing software is to request that program or match-playing software to implement a way to handle coordinates for larger sizes compatible with the way KataGo extended the GTP protocol for coordinates. The way I had KataGo implement seemed like by far the most natural way to extend the protocol for coordinates, and is the same as a common choice that board editing GUIs or even spreadsheets like Excel/Google Sheets use to label more coordinates - namely, after Z, you get AA, AB, AC, .... but I'd also be open for adding minor hacks to do a different format if necessary to be compatible with something else.
I'm posting this on the off chance that experts such as lightvector might see something worthwhile here.