Depth-first search. Depth-first search (DFS) is an algorithm for traversing or searching tree or graph data structures. One starts at the root (selecting some arbitrary node as the root in the case of a graph) and explores as far as possible along each branch before backtracking.
Derivative classification is: the incorporating, paraphrasing, restating, or generating in new form information that is already classified and the marking of the new material consistent with the classification of the source material, or the marking of the information in accordance with an authorized classification guide.
this does not mean that the information is unclassified derivative classifiers must carefully analyze the material they are classifying to determine the information it contains or reveals and evaluate that information against authorized classification guidance