Portion marking
Marking each section, paragraph or item of a document with its own classification, so readers can see which parts are sensitive, while the overall banner shows the highest level.
Portion marking applies classification at a finer grain than the whole document. Each paragraph, table, figure or title carries its own mark, while the overall marking at the top and bottom of the cover and first page shows the highest classification anywhere in the document. US classified national security information uses this practice under Executive Order 13526 and its implementing directive, 32 CFR Part 2001, where marks such as (U), (C), (S) and (TS) are placed at the start of each portion. Commercial organisations can apply the same idea with their own classification labels.
Portion marking and the high-water mark work together. The banner follows the high-water mark, so a mostly unclassified report containing one secret paragraph is handled as secret as a whole. The portion marks then show which content sets that level, which makes it possible to extract, share or declassify the less sensitive parts without reviewing everything again. Portion marking is one form of marking and labelling, and it supports the handling requirements set for each level.
Exam relevance: a scenario may describe a document with content at mixed sensitivity and ask how it should be marked, or how part of it can be released. Candidates are expected to recognise portion marking as the technique for mixed content, and to keep the document’s overall level at the highest portion it contains.