Mandatory signs are designed to succinctly communicate instructions to visitors. These signs use simple commands and pictures to easily communicate their message. This type of sign is required to be on a blue background and usually features a white safety symbol or simple picture illustration. While mandatory signs are not required by law, they are helpful to simply communicate what actions are required to people in your workplace. Examples of mandatory signs include ‘keep clear’, ‘keep locked’, and ‘report to reception upon arrival’.