The number is between 0 and 255. It specifies how much the number of distinct found words in a document affects its final score. This command has effect only when searching in m=any (any word) mode. 255 means maximum effect, 0 means ignore amount of found distinct words. The default value is 0. With a higher NumDistinctWordFactor value, search query consisting of several words will give more score to the documents containing all the given words and less score to the documents having only some of the words.