Classified U.S. national security information uses a very standardized set of markings so anyone who sees it immediately understands how sensitive it is, how to protect it, and how long it stays classified.

Core idea in one line

Standard markings include overall/banner classification , portion markings, the classification authority block, and other required labels like “Derived From” and declassification instructions.

The main standard markings

Think of a properly marked classified document as having several “layers” of labels.

  1. Overall (banner) classification marking
    • Shows the highest level of classification in the document (for example: TOP SECRET, SECRET, or CONFIDENTIAL).
 * Placed clearly at the top and bottom of the document’s first page, and often each page; for some agencies, also on covers and title pages.

 * Written in full words, all caps, in English; not abbreviated (so “TOP SECRET,” not “TS” in the banner).
  1. Portion markings
    • Each “portion” (paragraph, bullet, title, subject line, table cell, graphic, etc.) gets its own classification marking.
 * Standard portion marks:
   * (TS) = Top Secret
   * (S) = Secret
   * (C) = Confidential
   * (U) = Unclassified

 * The mark is placed at the beginning of the portion, for example:
   * “(S) This paragraph contains Secret information.”
  1. Classification Authority Block (CAB)
    This block explains who classified it, where it came from , and how long it stays classified.

It typically includes:

 * “Classified By” – the original or derivative classifier (person/position/office).

 * “Derived From” – source document(s) or classification guide(s); if multiple, often “Derived From: Multiple Sources.”

 * “Declassify On” – declassification date or event (for example, a specific date or “25X1”‑style exemption codes under the order).
  1. Page‑level classification
    • The highest classification on each page is marked at the top and bottom of that page.
 * If appropriate, even “UNCLASSIFIED” is printed at top and bottom to show that the page is not classified.
  1. Control and dissemination markings (when applicable)
    • These are added to the banner line to show extra handling rules beyond the basic classification level.
 * Examples include foreign government information (FGI) or limited distribution controls, formatted with slashes:
   * Example banner: “TOP SECRET//FGI//LIMITED DISTRIBUTION”.

 * Multiple control categories are separated by double slashes, multiple types within a category by single slashes.
  1. Restrictions for national security classification markings
    • Only “Top Secret,” “Secret,” and “Confidential” are used to identify classified national security information; no other words can be substituted.
 * Information cannot be classified for reasons unrelated to national security (for example, to hide errors or avoid embarrassment).

How this shows up in common formats

Even though the rules are standardized, they’re applied slightly differently to different media.

  1. Traditional documents (memos, reports, letters)
    • Banner line at top (and often bottom) with full classification level.
 * Portion markings for each paragraph, section, title, subject, table, figure, and so on.

 * Classification Authority Block on the face of the document (often on the first page).

 * Page‑level classification top and bottom of each page.
  1. Emails
    • Overall classification in a banner at the top before any text and at the bottom after all text.
 * Subject line portion‑marked (for example, “(U) Weekly Status Update” or “(S) Deployment Timeline”).

 * Body, signature block, and attachments portion‑marked just like a document.
  1. Electronic messages (IM, chats, etc.)
    • When retained, each page of the record gets a banner at top and bottom.
 * Portions (messages, links, graphics) are portion‑marked (U/C/S/TS, in parentheses).

 * A classification authority block is applied to the record.
  1. Non‑document materials (media, equipment, etc.)
    • Classification and handling information are affixed by tags, labels, or other means so recipients know protection requirements.

Simple example (text‑only illustration)

Imagine a two‑paragraph memo that is overall SECRET, but the first paragraph is unclassified and the second is secret.

  • Banner line (top of page):
    • SECRET
  • Body portions:
    • (U) This paragraph contains only general background that is not classified.
* `(S) This paragraph contains specific operational details and is Secret.`
  • Page markings:
    • “SECRET” at top and bottom of the page.
  • Classification Authority Block: for example:
    • Classified By: [Position Title]
    • Derived From: [Classification Guide Number]
    • Declassify On: 20491231

All of that together is what people mean by “standard markings for classified information” in the U.S. system.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.

TL;DR:
Standard markings = banner classification, portion markings (U/C/S/TS), page‑level classification, the classification authority block (Classified By / Derived From / Declassify On), and any required control or dissemination markings.