( ( ( ( ( lower ( case letters ) ) and ) numbers ) ( represent ( actual values ) ) ) ( , ( uppercase ( ( represent ( ( data fields ) ( ( whose values ) ( may ( ( vary ( from packet ) ) ( to packet ) ) ) ) ) ) ; ) ) ) )
(ROOT (S (S (NP (NP (JJR lower) (NN case) (NNS letters)) (CC and) (NP (NNS numbers))) (VP (VBP represent) (NP (JJ actual) (NNS values)))) (, ,) (NP (NN uppercase)) (VP (VBP represent) (NP (NP (NN data) (NNS fields)) (SBAR (WHNP (WP$ whose) (NX (NNS values))) (S (VP (MD may) (VP (VB vary) (PP (IN from) (NP (NN packet))) (PP (TO to) (NP (NN packet))))))))) (: ;)))
lower case letters and numbers represent actual values, uppercase represent data fields whose values may vary from packet to packet;
(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))))) (. .)))