NN - Not In (List) 
The Not In (NN) operator checks to see if Operand 1 is NOT contained in the list found in Operand 2. 
See $L in the 5.1.4. section.
Statement:			If an employee is unionized, charge $2.50 for union dues (into PC 1017)
Line	CMD	OT	Operand 1	OPER	OT	Operand2	OT	Operand3	If Goto	Else GoTo
00010	IF	DB	DUN.UNITE_CODE	NN	$L	UC-NON UNION UNITS			00100	99999
00100	LET	PC	1017	EQ	N	2.5			99999	
99999	EXIT								99999	

The UserCalc checks to see if the employee’s unit (Operand 1) is unionized by seeing that it is NOT included in the list of non-union units. If yes, the UserCalc goes to line 00100 to charge $5.