
     choice
        A choice object is a set of toggle buttons.  Each  button
        may  be  set on or off, but only one button may be active
        at a time. Syntax:

        choice={ label=... value=... name=... action=... item=...
        itemlist=... }

        The choice object consists of a text label and a  set  of
        buttons.  The value of the object on output is set to the
        value associated with the active button.

        name   defaults  to  "choice1",  "choice2"  etc.    label
        appears  adjacent  to  the buttons.  value is the initial
        value associated with the choice. It must match the value
        of  one  of  the  buttons, or by default it is set to the
        value of the first button.   action  is  an  action  that
        occurs when a button is pressed.

        Assigning a new value to a choice changes the  choice  to
        match  the new value. If the new value does not match any
        item's value the choice will be unchanged.

        item and itemlist are used to describe the  buttons  con-
        tained in a choice. You can either specify buttons one at
        a time with item, or in groups  with  itemlist.  See  the
        detailed  descriptions  of item and itemlist below. There
        is no limit on the number of items or itemlists used in a
        choice object.

        example:
        choice={ label="english colors" action="PRINT use $val "
                  item={ label=red } item={ label=green } item={ label=blue }
                    }
