10 CFR § 1017.16 - Unclassified Controlled Nuclear Information markings on documents or material.
(1) Front marking. The following marking must appear on the front of the document:
(2) Page marking. The marking “Unclassified Controlled Nuclear Information” must be placed on the bottom of the front of the document and on the bottom of each interior page of the document that contains text or if more convenient, on the bottom of only those interior pages that contain UCNI. The page marking must also be placed on the back of the last page. If space limitations do not allow for use of the full page marking, the acronym “UCNI” may be used as the page marking.
(3) Classified documents. UCNI front and page markings are not applied to a classified document that also contains UCNI. If a classified document is portion marked, the acronym “UCNI” is used to indicate those unclassified portions that contain UCNI.
(4) Obsolete “May Contain UCNI” marking. The “May Contain UCNI” marking is no longer used. Any document marked with the “May Contain UCNI” marking is considered to contain UCNI and must be protected accordingly until a Reviewing Official or Denying Official determines otherwise. The obsolete “May Contain UCNI” marking reads as follows:
Not for Public Dissemination May contain Unclassified Controlled Nuclear Information subject to section 148 of the Atomic Energy Act of 1954 (42 U.S.C. 2168). Approval by the Department of Energy prior to release is required.
(b) Marking material. If possible, material containing or revealing UCNI must be marked as described in § 1017.16(a)(1). If space limitations do not allow for use of the full marking in § 1017.16(a)(1), the acronym “UCNI” may be used.