All of the following are key concepts to determine the classification level of material you create except:

Determining the classification level of material involves understanding its importance and implications concerning national security. The key concepts that help in making this determination include relevance to national security, authority of information sources, and classification by content.

Relevance to national security is crucial because it directly influences whether the information should be classified or not. Information that could potentially harm national security if disclosed is often classified at various levels.

The authority of information sources matters because not all sources provide reliable or appropriately classified information. If a source is recognized as credible and authoritative, the information derived from it may warrant a higher classification.

Classification by content is another significant factor; it refers to the nature and specifics of the information itself. It assesses how sensitive the information is and which classification it falls under based on its content.

In contrast, the term "contained in," while it may seem related, does not serve as a key concept for determining the classification level. It does not address the nature or implications of the material itself, thus not aiding in the assessment of its classification. Therefore, this option is less relevant compared to the others listed.