anchor.diff:          if (present(error)) then
               error = internal_error
           else
  -            call check(error, att_name)
  +            call check(internal_error, att_name)
           endif
   
           call check( nf90_close(ncid), "closing:"//trim(filename))
  
positive.code:         if (present(error)) then
              error = internal_error
          else
              call check(error, att_name)
          endif
  
          call check( nf90_close(ncid), "closing:"//trim(filename))
  
negative.code:         if (present(error)) then
              error = internal_error
          else
              call check(internal_error, att_name)
          endif
  
          call check( nf90_close(ncid), "closing:"//trim(filename))
  