The character-level tags of the constituent " " 6 # 6 % " are the lower-cased word-level POS tag plus a positional letter.
the first character " " " is assigned the tag "nrb" where "nr" is from the word-level POS tag and "b" denotes the beginning character; the second (middle) character "# " gets the positional letter "m", signifying that it is in the middle, and the last character "% " gets the positional letter "e", denoting the end of the word.