( ( ( as usual ) ( an ( uppercase letter ) ) ) ( ( represents ( ( ( a pointer ) and ) ( ( a ( lowercase letter ) ) ( a ( data item ) ) ) ) ) . ) )
(ROOT (S (NP (ADJP (RB as) (JJ usual)) (NP (DT an) (JJ uppercase) (NN letter))) (VP (VBZ represents) (NP (NP (DT a) (NN pointer)) (CC and) (NP (NP (DT a) (JJ lowercase) (NN letter)) (NP (DT a) (NN data) (NN item))))) (. .)))
as usual an uppercase letter represents a pointer and a lowercase letter a data item.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VBD represented) (PP (IN by) (NP (DT a) (JJ single) (NN letter)))))) (, ,) (NP (JJ dominant) (NNS alleles)) (VP (VBP are) (VP (VBN represented) (PP (IN by) (NP (JJ uppercase) (NNS letters))))) (. .)))