1) Chinese invention
Found on
https://www.crosswordclues.com/clue/grid-reference
Grid references define locations on maps using Cartesian coordinates. Grid lines on maps define the coordinate system, and are numbered to provide a unique reference to features. Grid systems vary, but the most common is a square grid with grid lines intersecting each other at right angles and numbered sequentially from the origin at the bottom le...
Found on
http://en.wikipedia.org/wiki/Grid_reference
Numbering system used to specify a location on a map. The numbers representing grid lines at the bottom of the map (eastings) are given before those at the side (northings). Successive decimal digits refine the location within the grid system
Found on
https://www.encyclo.co.uk/local/21221
No exact match found.
