tape mounting

[HEDRICK at RUTGERS.ARPA]

From:  Charles Hedrick <HEDRICK at RUTGERS.ARPA>

Don't knock IBM systems in areas for which they are intended.  They may
not have EMACS, but IBM has put in more thought and had more experience
with data processing than the Unix world.  I don't know the context of
this comment, but if somebody is proposing a command to request the 
operator to mount a tape, the parameters mentioned are good ones:
  - vol_ser: Now and then people do make mistakes.  One of the major
	motivations for implementing labelled tape processing on Tops-20
	was so the system could automatically verify that the right
	tape had been mounted.  It is easy enough to mount the right
	tape on the wrong drive, or to get a couple of characters
	reversed and mount the wrong tape.  This can result in
	overwriting critical data.  Some of this is silly on a 4-user
	system that sits in the same room as the user terminals.  But on
	larger Unix timesharing systems, there are the same operational 
	requirements as for as IBM mainframe or a DEC-20.  My all means,
	tell the system what tape you want mounted, so it can check.
  - file name: this seems a bit 	

vol_ser, file mode density
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