 The PDP-11 Volume Preservation Utility (PRESRV) is a standalone
 program used to create copies of volumes in three formats:
 
	Files-11
 
	Logical tape
 
	Image
 
The general form of a PRESRV command line is:
 
	outdev:[label][/switches]=indev:[label][/switches]
 
 where:
 
 outdev		are the devices on which the output and input
 indev		volumes are mounted.  Their form is ddn:, where
		dd is the device name (two ASCII letters) and
		n is the octal unit number.  N is always 0 or 1
		unless the /UNIT switch is used.
 
 label		a label for the file when a volume is written as
		a logical tape.  It is used to identify files on
		logical tapes.  The label can consist of up to
		nine alphanumeric characters.  A label must be
		specified when the output is a logical tape.  It
		is optional for input.
 
 switches	one or more of the following optional switches
 
 
 
 Category	Switch	Function
 
 List		/HE	Causes a summary of PRESRV commands,
			switches, and defaults to be printed on
			the terminal
 
		/LI	Causes a list of all files on a logical
			tape volume to be printed on the terminal.
 
 Format		/FI	On input, indicates Files-11 format for
			reading or writing a disk volume.  On
			Output, overrides the /TP default or
			implied /IM.
 
		/IM	Indicates image mode, transfer all physical
			blocks of an input disk.  Never used with
			magtape.
 
		/TP	Indicates a logical tape format volume
			(which overrides the default image mode
			when device types are identical).
 
		/BL:n	Specifies a blocking factor for I/O
			operations.  Octal is assumed; decimal
			is indicated by a trailing decimal point.
 
 Administrative	/ER	Indicates that the PRESRV operation is to
			be terminate if an I/O error occurs.
 
		/FO	Indicates that the output disk pack is to
			be formatted before use
 
		/RW	Causes a cassette or magtape volume (either
			input or output) to be rewound at completion
			of PRESRV operation.  Note that PRESRV
			rewinds only the last volume of a multi-
			volume set when it is completely finished.
			Intermediate volumes must be rewound at the
			user.
 
		/VE	Causes the output volume to be verified
			after it is written.
 
 Magnetic tapes	/20	Indicates a recording density of 200 bpi
			for 7-track magtape.  Image transfers only.
 
		/55	Indicates a recording density of 556 bpi
			for 7-track magtape.  Image transfers only.
 
		/80	Indicates a recording density of 800 bpi
			for 7-track magtape.  Image transfers only.
 
		/PE	Indicates a recording density of 1600 bpi
			(phase encoded).  Can be used only for
			TU16/TE16/TU45/TU77 tape drives.
 
 Standalone	/CSR=n	Changes the control status register for a
			device type
 
		/UNIT=n	Sets the physical unit number of either
			PRESRV unit 0 or 1 to a value from 2 to 7.
 
		/VEC=n	Changes the interrupt vector address for
			a device type.
 
		/TM02=n	Sets the unit number of the TM02 formatter
			on an RH controller for a specific TU16
			magtape unit.  Note that /CSR, /UNIT,
			/VEC, and /TM02 can all be specified in
			the same command line.
 
		/TIM=mm/mm/dd/yy hh:mm[:ss]
			Specifies the correct time of day to the
			system.  All values are implied decimal.
 
		/BO	Causes PRESRV to "hardware" bootstrap
			the system from the specified device.
