I was hoping to manipulate it mostly because I am after the high performance of this particular function, as Laurent_R pointed out. I did write (with some help) my own sieving script to my liking, but it is really crude and slow performing. Dana Jacobsen (the author of most of these libraries) seems to be the person to contact, but if he isn't reachable, are there other people on this forum that are capable of making additions/changes to the libraries?