Notes for VMS users of XLISP-PLUS 3.05 on OpenVMS VAX (measured, 14-OCT-2026)
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* ERRSET only catches an error when *BREAKENABLE* is NIL.  Otherwise XLISP
  enters its break loop (prompt "1>") first:   (setq *breakenable* nil)
* READ-LINE at end of file signals an error, as in Common Lisp.  Use
  (read-line stream nil nil) to get NIL instead.
* DELETE-FILE removes the newest version of the file only (it is the C
  library remove).  A run that creates X.TMP and fails before deleting it
  leaves X.TMP;1 behind; the next OPEN of the name finds it.
* OPEN of a missing file for input is an error (not NIL).
* The Telnet terminal driver breaks output lines at the screen width; the
  same program with SYS$OUTPUT redirected to a file does not.
* Switches go in quotes (XLISP "-b" FILE.LSP): DCL changes case.  -b means
  batch: an uncaught error ends the program instead of entering the break loop.
  With SYS$INPUT redirected (DEFINE/USER SYS$INPUT NL:) the program exits at
  end of input.
* Ctrl/C returns to the top level.  Ctrl/Z ends the program (at a break
  level it first returns one level).  Ctrl/Y returns to DCL and leaves the
  program suspended: CONTINUE resumes it, any other command or LOGOUT ends
  it; no process is left behind.  (Measured once: a line typed immediately
  after CONTINUE was not seen as input; press Return first.)
* Floating point is G_floating (range 1E308).  Only the printed precision of
  a flonum is 6 digits (XLISP prints 1.41421 for the square root of 2).
* LOAD and RESTORE look a file name without device or directory up in the
  logical name XLPATH: (may be a search list) and then in the current
  directory.  XLISP_SETUP defines XLPATH unless you already did.
* (system "") is an error: no interactive subprocess is started.
* GET-KEY, POPEN and the graphics functions are not provided.
* The library in [.LSP] uses XLISP-PLUS's package system: some files want
  (load "common") first; "common" may report a name conflict with "provide"
  on a plain start, which is harmless for the examples.