What are the requirements for displaying my certification number?

A certification number must be displayed on all vehicles associated with a heating, air conditioning, or refrigeration entity; as well on all forms of advertising such as signs, billboards, business cards, website home pages, radio advertisements, television commercials, etc.; all invoices, estimates, quotes, letterhead, etc. Certification numbers are not required on employee uniforms. (ยง34-31-24(b))