The first code of the library worker is that there are no library worker codes.
There are a lot of codes, secret codes when it comes to working in an institution in common with other workers. These are codes of behavior, fraternity, sorority, codes of working people, codes of looking away, and codes about how the work is really done. Maybe everyone has their own code, and where they regularly overlap among the many, there are the true codes of the workplace.
I have written many times about workers' codes at the library I work at. I have a pretty fair understanding of many of them here. But what I have been an awful long time learning is that if you touch any of these codes directly enough, they are liable to blow up in your face.