Message precedence

Key takeaways

Message precedence belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Message precedence to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Message precedence from memory before moving on to harder problems.

Reference excerpt

Message precedence is an indicator attached to a message indicating its level of urgency, and used in the exchange of radiograms in radiotelegraph and radiotelephony procedures. Email header fields can also provide a precedence flag.

Early telegraphic procedures In the early days of telegraphy and radiotelegraphy, individual countries, and sometimes individual states, sometimes set their own regulations. For example, in the period around 1909, California required that "messages must, if practicable, be transmitted immediately on and in order of receipt; if not practicable, then in the following order:"

Messages from public agents of the State or of the United States on public business. Messages for immediate publication in newspapers, and not for any secret use. Message relating to sickness or death. Other messages in the order of filing.

International regulation Later in the development of telegraphy and radiotelegraphy, message precedence was nominally set by the International Telecommunication Union (ITU). Various ITU Regulations provide for the following priorities:

The U.S. Code of Federal Regulations, Title 47, has included the following priorities:

ETAT PRIORITE FLASH EMERGENCY IMMEDIATE EMERGENCY PRIORITY EMERGENCY URGENT The current U.S. Title 47 specifies these precedence designators for radiograms:

CCEB military precedence The Combined Communications Electronics Board (CCEB), a five-nation joint military communications-electronics organization (consisting of Australia, Canada, New Zealand, the United Kingdom, and the United States), uses the following message precedence designators, in descending order of importance:

FLASH (Z) is reserved for initial enemy contact messages or operational combat messages of extreme urgency. Brevity is mandatory. FLASH messages are to be handled as fast as humanly possible, ahead of all other messages, with in-station handling time not to exceed 10 minutes. Messages of lower precedence are interrupted on all circuits involved until the handling of the FLASH message is completed. IMMEDIATE (O) is reserved for messages relating to situations gravely affecting the security of the nation. It requires immediate delivery. Examples include reports of widespread civil disturbance, reports or warning of grave natural disaster, and requests for or directions concerning search and rescue operations. IMMEDIATE messages are processed, transmitted, and delivered in the order received and ahead of all messages of lower precedence. They are to be handled as quickly as possible, with in-station handling time not to exceed 30 minutes. Messages of lower precedence should be interrupted on all circuits involved until the handling of the IMMEDIATE message is completed. The use of the letter "O" comes from the original name for this level, "operational immediate". PRIORITY (P) is reserved for all traffic requiring expeditious action by the addressee or for conducting operations in progress when ROUTINE precedence will not suffice. PRIORITY precedence messages are processed, transmitted, and delivered in the order received and ahead of all messages of ROUTINE precedence. Examples include requests for supplies or equipment during the conduct of an operation, time-critical items requiring quick response, and situation reports. They are to be handled as quickly as possible, with in-station handling time not to exceed 3 hours. ROUTINE (R) is used for all types of message traffic justifying transmission by rapid means, but not of sufficient urgency to require higher precedence. ROUTINE precedence messages are delivered in the order received and after all messages of higher precedence. Examples include any message that requires the documentation of its transmission or delivery; messages concerning normal operations, programs, or projects; and periodic or consolidated reports. They should be handled as soon as traffic flow allows, but no later than the beginning of the next duty day. Flash Override (Y): The National Command Authority (usually the President of the United States) has access to a FLASH OVERRIDE (FO) capability. FO is not a precedence, but instead represents the authority and means to override all other traffic, including FLASH precedence messages. In written message traffic, the proword 'Y' is used to indicate a message having the authority to override all other traffic and is usually assigned to Emergency Action Messages (EAM).

Amateur radio message precedence The American Amateur radio community uses EMERGENCY, PRIORITY, WELFARE and ROUTINE precedence levels for ARRL Radiograms sent through National Traffic System nets.

See also IP precedence Multilevel precedence and preemption

References

External links "47 CFR 213.5 - Precedence designators". Legal Information Institute (LII). Electronic Code of Federal Regulations (e-CFR). Cornell Law School. "Message Precedence Designators". Georgia Wing. CAPR 100-1 Vol III (E) 3-2a. Civil Air Patrol. 21 Aug 2000. Archived from the original on Oct 18, 2004. "The National Communications System (NCS) Voice Precedence System". DISA Circular 310-70-1 Methods and Procedures (PDF). Defense Switched Network (DSN). Defense Information Systems Agency (DISA). Apr 21, 2012 [2006]. Archived from the original on Mar 13, 2008.{{cite book}}: CS1 maint: others (link)

Worked examples

Example 1 — a first encounter with Message precedence

Start with the simplest possible case. Write down what Message precedence claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Message precedence before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Message precedence ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Message precedence

In research: Message precedence appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Message precedence in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Message precedence is common in secondary-school and first-year university syllabi. It links to neighbouring topics Military communications, so understanding it makes those chapters shorter.
In everyday life: Look for Message precedence outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Message precedence in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Message precedence means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Message precedence out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Message precedence in simple terms?

Message precedence is an indicator attached to a message indicating its level of urgency, and used in the exchange of radiograms in radiotelegraph and radiotelephony procedures. Email header fields can also provide a precedence flag.

Why does Message precedence matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Message precedence?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Message precedence.