A question about solr score

[zx zhang]

Hi, everyone!
As we known, solr uses lucene scoring.
This score is the raw score. Scores returned from Hits aren't
necessarily the raw score, however. If the top-scoring document scores
greater than 1.0, all scores are normalized from that score, such that
all scores from Hits are uaranteed to be 1.0 or less.
Now it is my question, I always get scores of some documents which are
above 1.0, even some get up to 10.0!
Why?
I will really appreciate your reply.