The very first paragraph of the “Classified Information Nondisclosure Agreement” she signs states, “As used in this Agreement, classified Information is marked or unmarked classified Information.”
According to Executive Order 12958, which is in effect at the time, since she is the secretary of state, she is given the authority to classify or declassify any State Department information she wants. However, as part of her nondisclosure agreement (NDA), she has the legal responsibility to identify and safeguard any classified information originating from other government agencies, whether that information is marked classified or not. (The Washington Post, 2/4/2016) (US Department of State, 11/5/2015)
This is one of two NDAs Clinton signs on this day.