If you look at the word in my screenshot with the red box around it (Love), the blue dots in the module selection mark other modules with an entry that matches that word - it could be a variation, like 'loved' or 'loves'. If you click on the module marked with the blue dot, it will open with the matching entry. The blue dots are actually next to non-editable books/commentaries as well - look at WTypes, the first entry is "00 Introduction" and the blue dot shows up in other books with an entry of 00 Introduction.