FUNCTION WEEKDAY#(M,D,Y : INTEGER):INTEGER;

{ COMMENT :
	GIVEN THE DATE , CALCULATES THE DAY OF THE WEEK AS A NUMBER
  BETWEEN 0 AND  6 (INCLUSIVE) , DAY 0 BEING SUNDAY.SHOULD WORK FOR
  ALL DATES SINCE 2/28/00 A.D..
	NOTE THAT THE EXTERNAL PROCEDURE ZELLER IS USED : THIS MUST
  BE DECLARED AT A HIGHER LEVEL , AS MUST BE THE VARIABLE ZELLER# 
  AND ITS TYPE " COMPOSITE".	}

CONST
	K_MOD_7		= 2;
VAR
	K_DAYS,
	U_DAYS	: INTEGER;

BEGIN
 ZELLER(M,D,Y,ZELLER#);
 K_DAYS		:= ZELLER#.KILO_DAYS  * K_MOD_7;
 U_DAYS		:= ZELLER#.UNIT_DAYS  MOD 7;
 WEEKDAY#	:= (U_DAYS + K_DAYS) MOD 7;
END; { OF : FUNCTION WEEKDAY# }