Transformations

  Data in any variable can be transformed to new values, and new variables
can be created by transformation.  Values are transformed by all the usual
arithmetic operators, and the variables subjected to transformation may be
old or new.

  For example, if a variable is named 'SCORE' in the list of variable names,
its values would be transformed by;
		SCORE = SCORE-5     or     SCORE = SCORE + RESULT
In the last example, 'RESULT' would also be a variable in the variale list
named earlier.
  New variables are created by assigning them a name not used before in the
variable list.  For example;
		SCORE2 = SCORE + 5   or    TOTAL = SCORE + SCORE1
In the last example, both 'SCORE' and 'SCORE1' would exist in the list of
variable names, and the new variable 'TOTAL' would be added to the list.

  Only two arguments may be used to the right of the = sign, (and only one
argument to the left of the = sign).