Regulatory signs:

Regulatory signs are often rectangular and white with black markings and are used to indicate what things a driver must or must not do in a designated area. They may display speed limits, prohibit passing or turning, or clarify any other driving regulation.

• Are placed in every location where there is a present danger.
• Indicate what a driver must or must not do.
• Are diamond-shaped and yellow or green.
• May warn drivers that they are approaching a school zone.