NUMBER:  23

  ERROR CODE:  F

  MESSAGE TEXT:  BACKSPACE error

  EXPLANATION:  One of the following conditions occurred:

   o  The file was not a sequential organization file.

   o  The file was not opened for sequential access.  (A unit opened
      for append access may not be backspaced until a REWIND
      statement is executed for that unit.)

   o  RMS detected an error condition during execution of a BACKSPACE
      statement.