You must select the map projection (Long/Lat, UTM-32, etc.) in which you want to specify the horizontal spatial information.
The line is defined by defining a polyline in the horizontal domain. The polyline is given by a number of geo-referenced points. A minimum of two points is required. The polyline is composed of a sequence of line segments. The line segments are straight lines between two successive points. The geographical coordinates are taken from the dialog or from a file. The file format is an ascii file with three space separated items for each of the points on separate lines. The first two items must be floats (real numbers) for the x- and y-coordinate (Easting and Northing or Longitude and Latitude). The third item is unused (but must be specified).
If "Spectral parameters" is selected for the field type values for the points on the line are determined by piecewise linear interpolation. Hence, the point values are the discrete values for the elements in which the specified points are located. The element number and the horizontal coordinates of the centre of the element and z-coordinate are listed in the log file.