anchor.diff:      interface
           subroutine plrgb1( r, g, b )
               use plplot_types
  +            implicit none
               integer(kind=plint) :: r, g, b
           end subroutine plrgb1
       end interface
  
positive.code:     interface
          subroutine plgpage( xpmm, ypmm, xwid, ywid, xoff, yoff )
              use plplot_types
              real(kind=plflt) :: xpmm, ypmm
              integer(kind=plint)          :: xwid, ywid, xoff, yoff
          end subroutine plgpage
  
negative.code:     interface
          subroutine plgcol0a( icol, r, g, b, a )
              use plplot_types
              implicit none
              integer(kind=plint) :: icol, r, g, b
              real(kind=plflt) :: a
          end subroutine plgcol0a
  