10.5  SYMBOLS 

Symbols are 0O to 9O or any legal UGSYS duplex character set pair.  "NONE"
indicates no symbol.  "  " or "DOT" produces a  dot.   If  the  symbol  is
omitted  it is assumed to be NONE and the datum is plotted by default as a
point rather than a symbol.  This may be modified by SET SYMBOL.   If  you
wish  to  use  the  number  1 as a symbol it must be enclosed in quotes or
apostrophes ("1").