anchor.diff:              read(tag,*) lim1,lim2,dz
           elseif (tag(1:2).eq.'-v') then
               vrb = 1
  +        elseif (tag(1:2).eq.'-D') then
  +            saturate = 1
           elseif (tag(1:2).eq.'-d') then
               call usage('long')
           else
  
positive.code:     ! User-defined variables
      real :: hue1,hue2,light1,light2,chroma1,chroma2,lim1,lim2
      character(len=200) :: option,convert1,convert2,gmt
      integer :: ncolors
  
      ! Parse command line
      call gcmdln(option,hue1,hue2,light1,light2,chroma1,chroma2,ncolors,convert1,convert2,&
                  gmt,lim1,lim2)
      if (vrb.gt.0) then
          write(0,*) 'Color mapping option: ',trim(option)
          write(0,*) 'Hue range:            ',hue1,hue2
  
negative.code:     vrb = 0
      dz = -1.0
      gmt = 'none'
      saturate = 0
      narg = iargc()
      if (narg.eq.0) call usage('')
      i = 1
  