anchor.diff:  C----
         if (p.eq.0) open(unit=12,file=ofile,status='unknown')
         if (c.eq.0) then
  -          open(unit=11,file=ifile,status='old')
  -  102     read(11,'(A240)',end=101) arg
  +          if (ifile.eq.'stdin') then
  +              u = 5
  +          else
  +              u = 11
  +              open(unit=u,file=ifile,status='old')
  +          endif
  +  102     read(u,'(A240)',end=101) arg
                 call getfmt(arg,ifmt)
                 call rdarg(arg,ifmt,opt,long)
                 call getans(ans,opt,long)
  
positive.code:       CHARACTER*40 ifile,ofile,tag
        CHARACTER*240 arg
        INTEGER i,narg,j,opt,p,c,long
        ifile = 'none'
        ofile = 'none'
        opt = 0
        long = 0
        p = 0
        c = 0
        arg = 'none'
        narg = iargc()
  
negative.code:           write(0,*) '!! Error: Type of date computation unspecified'
            call usage('!! Use -nday or -date')
        endif
        if (c.eq.0.and.ifile.ne.'stdin') then
            inquire(file=ifile,EXIST=ex)
            if (.not.ex) call usage('!! Error: no input file: '//ifile)
        endif
  