What type of data could reasonably be expected to cause damage to national security?

The type of data that could reasonably be expected to cause damage to national security when improperly disclosed is classified as "Confidential." This classification is specifically designed for information that, if released, could cause damage to national security but not as severe as information classified as "Secret" or "Top Secret."

The "Confidential" designation indicates that the information is sensitive and requires certain safeguards to prevent unauthorized access. It reflects a balance between the level of sensitivity and the potential consequences of leaking the data. While "Top Secret" data carries the most critical risk of causing exceptionally grave damage to national security, "Confidential" is more accessible while still being protective of national interests.

In this context, "Secret" and "Top Secret" represent higher classifications with more severe implications for national security than "Confidential." "Controlled Unclassified Information" (CUI), while also sensitive, does not typically pose a risk significant enough to cause damage to national security in the same way that "Confidential" information does. Thus, "Confidential" is the appropriate classification when considering data that could lead to a reasonable expectation of causing damage to national security.