Menus

Some parameters offer menus from which you select an option. You do not have to enter the full option string, but merely a string that selects a choice unambiguously. In many cases this can be as little as a single character. Here is an example,

     MODE - Method for selecting contour heights /'Free'/ > ?
         The method used to select the contour levels.  The options are
         described below.

           "Area"      - The contours enclose areas of the array for
                         which the equivalent radius increases by equal
                         increments.  You specify the number of levels.
           "Automatic" - The contour levels are equally spaced between
                         the maximum and minimum pixel values in the
                         array.  You supply the number of contour
                         levels.
           "Free"      - You define a series of contour values
                         explicitly.
           "Linear"    - You define the number of contours, the start
                         contour level and linear step between contours.
           "Magnitude" - You define the number of contours, the start
                         contour level and step between contours.  The
                         step size is in magnitudes so the nth contour
                         is dex(-0.4*(n-1)*step) times the start contour
                         level.

where an F would be sufficient to select the "Free" option, but at least two characters would be needed if you wanted "Area" or "Automatic".

Some parameters permit a mixture--a choice from a menu, or a numerical value within a range. The options are described in full in application specifications.