1.  Basic angle of the initial production domain and subdivisions of this basic angle are provided to manage cases where the recommended unit of 10^-6 degrees is not applicable to describe the extreme longitudes and latitudes, and direction increments. For these last six descriptors, the unit is equal to the ratio of the basic angle and the subdivisions number. For ordinary cases, zero and missing values should be coded, equivalent to respective values of 1 and 10⁶  (10^-6  degrees unit).

2. The stretching is defined by three parameters:
  (a) The latitude in degrees (measured in the model coordinate system) of the "pole of stretching";
   (b) The longitude in degrees (measured in the model coordinate system) of the "pole of stretching"; and
   (c) The stretching factor C in units of 10^-6 represented as an integer.
The stretching is defined by representing data uniformly in a coordinate system with longitude λ and latitude 0^1, where:

0¹ = sin^-1 [(1- C²) + (1 + C²) sin 0] / [(1 + C²) + (1 - C²) sin 0]

and λ and 0 are longitude and latitude in a coordinate system in which the "pole of stretching" is the northern pole. C = 1 gives uniform
resolution, while C > 1 gives enhanced resolution around the pole of stretching.

3.  A quasi-regular grid is only defined for appropriate grid scanning modes.
Either rows or columns, but not both simultaneously, may have variable numbers of
points or variable spacing. The first point in each row (column) shall be positioned
at the meridian (parallel) indicted by octets 47-54. The grid points shall be evenly spaced in latitude (longitude).