I am completely naive and new to NLP. I am following a course on NLP on coursera. As I was studying about parse tree, I came across following sentence to parse:
Because the CD had an effective yield of 13.4 % when it was issued in 1984 , and interest rates in general had declined sharply since then , part of the price Dr. Blumenfeld paid was a premium -- an additional amount on top of the CD 's base value plus accrued interest that represented the CD 's increased market value .
And partial parse tree to this sentence is:
(S (SBAR-PRP (IN Because) (S (S (NP-SBJ (DT the) (NNP CD)) (VP (VBD had) (NP (NP (DT an) (JJ effective) (NN yield)) (PP (IN of) (NP (CD 13.4) (NN %)))) (SBAR-TMP (WHADVP-4 (WRB when)) (S (NP-SBJ-1 (PRP it)) (VP (VBD was) (VP (VBN issued) (NP (-NONE- *-1)) (PP-TMP (IN in) (NP (CD 1984))) (ADVP-TMP (-NONE- *T*-4))))))))
I am not able to get meaning of -NONE- T-4 and -NONE- *-1. Anyone can help me?