In the book The Name of This Book is Secret what does Dr L stand for?

In the book "The Name of This Book is Secret" by Pseudonymous Bosch, Dr. L stands for Dr. Lucifer.

He is a mysterious and powerful figure who is the leader of a secret society called the "Secret Order of the Librarians." He is also the villain of the story, and he is responsible for a lot of the chaos and destruction that happens.