ow -- Option Warning

               default range              syntax
                 1,$                      ow[integer]

        The "w" option is the  Warning  column  number.   Typing  "ow"
        followed by a number sets the warning column threshold; simply
        typing  "ow"  causes  its current value to be displayed.  When
        you are about to type into a column of equal or greater number
        than the warning column, the number  of  the  column  you  are
        about  to type into is displayed on the bottom line along with
        the string "col  ".

        For general information about the option command, type "ho".