What type of marking indicates that material is sensitive and has no declassification instruction?

The marking that indicates material is sensitive and has no declassification instruction is known as "CNWDI," which stands for "Controlled Nuclear Weapon Design Information." This marking is specifically used for information that is critical to national security and is subject to strict control. It signifies that access to this information is restricted and that it should be protected accordingly.

Materials marked with CNWDI are considered sensitive due to their potential impact on national defense and military strategy. Since these materials lack a declassification instruction, it is understood that they are to be treated as permanently restricted, and proper protocols must be followed for handling and disseminating this information. This helps ensure that sensitive details related to nuclear weapon design remain confidential and are only accessible to those with the necessary clearances.

Other types of markings, such as the warning notice and RD warning notice, serve different purposes related to the classification or handling of specific information but do not convey the particular permanence and sensitivity associated with CNWDI.