SUB - Subtract
Subtract Operand 3 from Operand 2, store result in Operand 1
Operand 1 = Operand 2 - Operand 3
Example:			Subtract PC 110 from PC 100 and store the value in the Variable PC100 less PC110.
Line	CMD	OT	Operand 1	OPER	OT	Operand2	OT	Operand3	If Goto	Else GoTo
00010	LET	V	PC 100 LESS PC 110	SUB	PC	100	PC	110	99999	00110