LATLON

     LATLON specifies the latitude and longitude grid lines to be drawn.  
     The line color, line type, line width, label frequency and increment 
     are separated by slashes:

	color/line_type/line_width/x-freq;y-freq/x-inc;y-inc/lt_label;ln_label/format

     The label frequency specification contains the latitude and longitude 
     label frequencies separated by a semicolon.  The increment specification 
     contains the latitude and longitude increments in degrees separated by 
     a semicolon.

     If the color is 0 or LATLON is blank, grid lines are not drawn.  The 
     latitude and longitude increments will default to 10 degrees.  The 
     label frequency defaults to 1.

     The latitude and longitude labels refer to the latitude at which to label
     the longitudes lines and the longitude at which to label the latitude lines.
     The defaults for the latitude and longitude value placements if either or
     both are not specified are usually the left side for latitude labeling
     and the bottom for longitude labeling.

     The format value specifies the current format of the labels.  If format is
     equal to 1, the latitude and longitude labels have a '-' prepended to the
     southern and western number labels.  If the format is equal to 2, 'N', 'S', 
     'E' and 'W' are appended to the latitude and longitude labels. The default
     is that the '-' will be prepended to the southern latitudes and western
     longitudes.

     Examples:

	LATLON	= 1

 		Lat/lon grid lines are drawn every 10 degrees in color 1 using 
 		line type 1 and line width 1.

	LATLON	= 4/8/3/2/5;5

 		Lat/lon grid lines are drawn every 5 degrees in color 4 using 
 		line type 8 and line width 3.  Every other line is labelled.

	LATLON   = 24/12/1/2;2/4;4/48.;-100./2

 		Lat/lon grid lines are drawn every 4 degrees in color 24 using 
 		line type 12 and line width 1.  Every other line is labelled.
 		The latitude labels appear on 100.0 W longitude and the 
 	        longitude labels appear on 48 N latitude appended to the 
 	        numerical labels.