"NX" = get next file in alphabetical sequence
"NB" = get previous file in sequence (NB = next back)

This offers a quick way to go through a sequence of files that have been
named with their last letters in alphabetical order.
  Example: Suppose you have a series of files with the following names -
            SONAA.X, SONAB.X, SONAC.X
            SONBA.X, SONBB.X, SONBC.X, SONBD.X
            SONCA.X, SONCB.X, SONCC.X
            etc.

  Once you have SONAA.X on the screen you may proceed to SONAB.X by just
  typing "NX".  Each time you type "NX" again you will move on to the next
  file.  Typing "NB" will move to the next back - but when you get to a file
  whose last letter is "A" it will next retrieve the next one back that ends
  with "A".  Thus you can back up from SONBD.X to SONBC.X, etc. to SONBA.X, but
  the next backup will take you to SONAA.X.

   MAKE SURE ALL EDITING IS SAVED BEFORE TYPING "NX" OR "NB"!!!

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