Colo. Rev. Stat. § 22-42-115
The bonds issued under the provisions of this article shall be numbered consecutively, beginning with number one. The board of education of the district is authorized to prescribe the form of such bonds. Said bonds shall recite that they are issued pursuant to this article, and said bonds shall be signed by the president of the district, bear an impression of the seal of the district, and be attested by signature of the secretary. Coupons, if any, evidencing the interest thereon shall bear the signature of the president of the district, which may be affixed by him in person, or it may be an engraved or lithographed facsimile thereof. At the discretion of the board of education, any school bonds may be issued with privileges for registration of such bonds for payment as to principal, interest, or both. In the execution of bonds authorized pursuant to this article, the board of education may provide for the use of facsimile signatures and facsimile seals in the manner set forth in article 55 of title 11, C.R.S.
C.R.S. § 22-42-115