{}
{  The purpose of this request is to initialize a tape unit.  It must be
{ done after each assign and before any I/O operations are done to a unit.
{}
{       IOP$INITIALIZE_TAPE_UNIT (^TAPE_FILE_DESCRIPTOR, LOGICAL_UNIT_NUMBER,
{         STATUS)
{}
{ TAPE_FILE_DESCRIPTOR: (input) Pointer to the descriptor for the tape file.
{}
{ LOGICAL_UNIT_NUMBER: (input) This parameter specifies the unit to be
{       initialized.
{}
{ STATUS: (output) This parameter specifies the request status.
{       Condition:
{               ioc$unrecognized_unit_id
{               ioc$improper_sequence
{       Identifier: ioc$physical_io.
{}


