14.7.3 STATUS, VMSSTATUS, and RMSSTATUS Functions
  The STATUS function accesses the status longword that con-
  tains characteristics of the last opened file. If an error occurs
  during an input operation, the value of STATUS is unde-
  fined. If an error does not occur, the six low-order bits of the
  returned value contain information about the type of device
  accessed by the last input operation. These bits correspond to
  the following devices:

  .
        If bit 0 is set, the device type is a record-oriented device.
  .
        If bit 1 is set, the device type is a carriage control device.
  .
        If bit 2 is set, the device type is a terminal.
  .
        If bit 3 is set, the device type is a directory oriented device.
  .
        If bit 4 is set, the device type is a single directory device.
  .
        If bit 5 is set, the device type is a sequential block-oriented
        device (magnetic tape or TK50).

  Both the VMSSTATUS and RMSSTATUS functions are
  used to determine which non-BASIC error caused a re-
  sulting BASIC error. In particular, VMSSTATUS can be
  used for any non-BASIC errors, while RMSSTATUS is used
  specifically for RMS errors. For more information about
  these functions, see Chapter 16 and the DEC BASIC and
  VAX BASIC for OpenVMS Systems Reference Manual .