The concept where new material aggregates or brings together pieces of information that are not individually classified but when combined render the material classified is called "Classification by Compilation." This means that while individual pieces of data may be unclassified alone, their aggregation forms classified information because of the relationships or new context they reveal when combined.
In other words, classification by compilation refers to derivative classification that arises from combining separate pieces, which individually might be unclassified, but together they create classified material.
