> This means that de facto, most of the world has subscribed to American mapping conventions. That is overstating the situation; ITRS is the key standard here

> This means that de facto, most of the world has subscribed to American mapping conventions. That is overstating the situation; ITRS is the key standard here and it's maintained by IERS. I think WGS-84 and ITRS are somewhat aligned these days, but the exact relationship is not clear to me. Various regional reference systems are also still widely used, for example ETRS89 in Europe, which is afaik semi-independently defined by EPN (EUREF Permanent Network). Most notably Galileo GNSS does not use WGS-84. The key difference between various other systems and the Chinese one is just that for the other systems the conversions to and from WGS-84 are available to high precision.