The standard operating procedure of the TSA, also referred to as SOP, is hundreds of pages long. Of course, very few people working security have actually read the entire document, and even fewer remember all of it. Agents tend to use common sense and go by word-of-mouth when using their security knowledge. As a result, you may find an agent not letting through an item that you know is allowed or even treating you in a way that is strictly against regulation. If this happens, you can ask your agent to call a supervisor and double-check the SOP.