POSITION = pos

  pos   Is a scalar default character variable that is assigned
        one of the following values:

  'REWIND'    If  the file is connected with its position
              at its initial point

  'APPEND'    If the file is connected with its position
              at its terminal point (or before its end-of-file
              record, if any)

  'ASIS'      If the file is connected without changing
              its position

  'UNDEFINED' If the file is not connected, or is connected
              for direct access data transfer and a REWIND
              statement has not been performed on the unit.