If the plane table is not horizontal in a direction at right angles to the alidade, the line of sight is parallel to the fiducial edge only for ............

If the whole circle bearing of a line is 270° its reduced bearing is ............

The rise and fall method ............

The length of a link of Gunter's chain is ............

A fixed point of reference of known elevation is called ............

When the measured length is less than the actual length, the error is known as ............

The rise and fall method of reduction of levels, provides a check on ............

The horizontal angle between true meridian and magnetic meridian, is known ............

Check lines (or proof lines) in Chain Surveying are essentially required ............