Horizontal Control

Horizontal Control Network is a network of known horizontal geographic positions, referenced to geographic parallels and meridians or to other lines of orientation such as plane coordinate axes.平面控制网（Horizontal Control Network）是由已知水平地理位置点构成的网络，其定位参考基准为地理纬线与经线，亦或是其他定向基准线（如平面坐标轴）。