Mention three features of arbitrary grid system.

Three features of arbitrary grid system are:

1. The south-west corner or the bottom-left corner of topo sheet is always taken as the starting point or the point of reference for the grid.
2. The vertical grid lines, drawn from north to south, are called the eastings. The eastings are so called because they lie towards the east of the south-west corner.
3. The horizontal grid lines, drawn from east to west, are called the northings. The northings are so called because they lie towards the north of the south-west corner.