In this section the following words have the meanings indicated. “Certificate of guarantee” means an instrument that is issued: by a nonprofit association of contractors, or its wholly owned subsidiary that is approved to operate by a county; and on behalf of a contractor for the purpose of satisfying: county bond requirements for public improvements; or other county bond requirements. “Contractor” means a person that, for a fixed price, commission, fee, or percentage, undertakes to bid on or accepts or offers to accept orders or contracts to perform or supervise the construction, improvement, or maintenance of a building, structure, or road. This article does not apply to a certificate of guarantee. A county: may honor certificates of guarantee; but is not required under this article to honor certificates of guarantee.