IN - In (List) 
The In (IN) operator checks to see if Operand 1 is contained in the list found in Operand 2. 
See $L in the 5.1.4. section. 
Statement:			If an employee is non-union, charge $5.00 for coffee service (into PC 1015)
Line	CMD	OT	Operand 1	OPER	OT	Operand2	OT	Operand3	If Goto	Else GoTo
00010	IF	DB	DUN.UNITE_CODE	IN	$L	UC-NON UNION UNITS			00100	99999
00100	LET	PC	1015	EQ	N	5			99999	
99999	EXIT								99999	

Here the UserCalc checks to see if the employee’s unit (Operand 1) is included in the list of non-union units (Operand 2). If yes, the UserCalc goes to line 00100 to charge $5.