Which marking indicates that a message is classified information not meant for public access?

The marking "For Official Use Only" (FOUO) clearly identifies information that is sensitive and intended only for specific government or organizational personnel. This designation protects the information from unauthorized access and dissemination, ensuring that only those with a valid need-to-know basis can view it. FOUO is crucial in maintaining the integrity of information that, while not classified at the highest levels, still requires safeguarding from public access to prevent potential misuse or compromise of sensitive information.

In contrast, the other options relate to different forms of information security but do not specifically denote the same level of restriction for public access as FOUO does. Encrypted for Transmission (EFTO) pertains more to the security of information during transit rather than its classification. Limited Distribution (LIMDIS) indicates that information is confined to a certain audience but does not carry the same implication of public inaccessibility as FOUO. Special Category (SPECAT) typically refers to sectors of information that are subject to additional categories of protection, which may or may not include public access restrictions. Thus, FOUO is the most appropriate choice for indicating a classification level specifically intended to restrict public access to sensitive information.