$
G+:-@ !5+;-<5#0125#7 *P1#45;54@
!5+;-<5#R5;54#(D
N G<<5@@#<125#(Y'&&&#
N >,:5#,.2#:-05#<E,./5#
N G3:1#@:,+:#9+5@5:
N >-@94,?@#,44#9+5@5:#9,+,05:5+@
Two$Service$Levels$with$different$access$codes
!5+;-<5#R5;54#AD
N *5<E.-<-,.@#,<<5@@#
N M+5@5: 5.;-+1.05.:
N *+,.@F5+#1F#9+5@5:@#;-,#,.#Q!Z#^5?
N [,4-L+,:-1.#1F#@5.@1+@
N Z4,<^Z1H 21P.41,2-./