For example, we have the string " (specialistlevel)/w 1 /w 2 /w 3 / (discussion)", and " (specialist-level)" is TOP and " (discussion)" is NEXT.
we can have the feature "TN0:3+:D1-L-HIGH" for TOP and NEXT, because the word distance is 4(3+) and " (specialist-level)-(discussion)" belongs to the bucket "D1-L-HIGH".