Portion Marking
Portion marking is the practice of labeling each individual section of a classified or controlled document—paragraphs, titles, bullets, captions—with its own classification or control level so readers can see exactly which parts are sensitive.
Portion marking is the granular labeling of every discrete portion of a record—each paragraph, subparagraph, title, heading, bullet, table, and caption—with an abbreviated marking showing its own classification level (for example, U for Unclassified, C for Confidential, S for Secret) or control category. The overall classification of a document is determined by its most sensitive portion, so portion markings let users identify the source of that determination at a glance.
In recordkeeping, portion marking matters because it drives downstream actions long after creation. It enables accurate redaction, supports declassification review, and makes it possible to extract or release only the unsensitive portions of a record under access requests. A reviewer can lift an Unclassified paragraph from an otherwise Secret memo without re-reading and re-adjudicating the entire file.
A useful distinction: the banner or header marking states the document’s overall level, while portion markings state the level of each piece. A document marked Secret overall may contain individual paragraphs marked (U), (C), and (S)—and only the (S) portion compels the higher banner.