V=VLREAD()
$(VARIABLE LIST READ.  V, A LIST OF VARIABLES, IS READ FROM THE INPUT
STREAM.  ANY PRECEDING BLANKS ARE SKIPPED.)
     SAFE C.
(1)  $(READ VARIABLES.)  V=().  C=CREADB().  IF C NE $=( THEN GO TO 2.
     C=CREADB().  IF C=$=) THEN RETURN ELSE BKSP.  REPEAT
     (  VL=VREAD().  V=COMP(VL,V).  C=CREADB().  IF C=$=) THEN
     ( V=INV(V).  RETURN ) ELSE IF C NE $=, THEN GO TO 2  ).
(2)  $(ERROR.)  PRINT $(ERROR FOUND BY VLREAD.).  DIBUFF.  STOP..