16-line message format, or Basic Message Format, is the NATO standard military radiogram format for the manner in which a paper message form is transcribed throug hvoice, Morse code, or Teletypewriter transmission formats. The overall structure of the message has three parts: HEADING (which can use as many as 10 of the format's 16 lines), TEXT (line 12), and ENDING. This heading is further divided into procedure, preamble, address, and prefix. Each format line contains pre-defined content. An actual message may have fewer than 16 actual lines, or far more than 16, because some lines are skipped in some delivery methods, and a long message may have a TEXT portion that is longer than 16 lines by itself.
This radiotelegraph message format (also "radio teletype message format", "teletypewriter message format", and "radiotelephone message format") and transmission procedures have been documented in numerous military standards, going back to at least World War II-era U.S. Army manuals.
The 16-line format and procedures for transmitting it vary slightly depending on the communications medium, but all variations are designed to be harmonious and the procedures describe how to convert (refile) between the formats.
When sent as an ACP-126 message over teletype, a 16-line format radiogram would appear similar to this:
RFHT DE RFG NR 114 R 151412Z MAR FM CG FIFTH CORPS TO CG THIRD INFDIV WD GRNC BT UNCLAS PLAINDRESS SINGLE ADDRESS MESSAGES WILL BE TRANSMITTED OVER TELETIPEWRITER CIRCUITS AS INDICATED IN THIS EXAMPLE BT C WA OVER TELETYPEWRITER NNNN
Some of the format lines in the above example have been omitted for efficiency. The translation of this abbreviate format follows:
| Format Line | Message Text | Explanation |
|---|---|---|
| Line 2 | RFHT | Station being called, which will receive the message |
| Line 3 | DE RFG NR 114 | Sent by radio station having the callsign RFG, station serial number 114 |
| Line 5 | R 151412Z MAR | Routine precedence, March 15, 2:12pm UTC in Date-time group format |
| Line 6 | FM CG FIFTH CORPS | The message is from CG FIFTH CORPS |
| Line 7 | TO CG THIRD INFDIV | The message is to CG THIRD INFDIV |
| Line 10 | WD GRNC | Accounting symbol (WD); word groups have not been counted (GRNC) |
| Line 11 | BT | Section separator between heading and text |
| Line 12 | UNCLAS PLAINDRESS SINGLE ADDRESS MESSAGES WILL BE TRANSMITTED OVER TELETIPEWRITER CIRCUITS AS INDICATED IN THIS EXAMPLE | Message content is unclassified, and the message is sent with a misspelled word, "TELETIPEWRITER" for example purposes. |
| Line 13 | BT | Section separator between text and the ending |
| Line 15 | C WA OVER TELETYPEWRITER | corrects (C) word after (WA) "OVER" to "TELETYPEWRITER" |
| Line 16 | NNNN | end-of-message indicator |
Example message in four different formats:
| Format Line | Telegraph Radiogram (ACP-124) | Voice Radiogram (ACP-125) | Radioteletype Radiogram (ACP-126) | Tape Relay Radiogram (ACP-127) | ACP-127 Supl. |
|---|---|---|---|---|---|
| 1 | VZCZC051 UU | VZCZC051 UU | VZCZC051 UU | ||
| 2 (or 2&3) | CALLED_CALLSIGN THIS IS CALLING_CALLSIGN MESSAGE NUMBER 051 | CALLED_CALLSIGN DE CALLING_CALLSIGN NR 051 | RR CALLED_CALLSIGN | RR CALLED_CALLSIGN | |
| 3 | DE CALLING_CALLSIGN 0051 22/1856Z | DE CALLING_CALLSIGN #0051 1121857 | |||
| 4 | TRANSMISSION INSTRUCTIONS/OP. SIGS | ZNR UUUUU TRANSMISSION INSTRUCTIONS/OP. SIGS | ZNR UUUUU TRANSMISSION INSTRUCTIONS/OP. SIGS | ||
| 5 | ROUTINE TIME 221855Z APR 2015 | R 221855Z APR 2015 | R 221856Z APR 2015 | R 221857Z APR 2015 | |
| 6 | FROM ORIGINATION PLAIN LANGUAGE ADDRESS | FM ORIGINATION PLAIN LANGUAGE ADDRESS | FM ORIGINATION PLAIN LANGUAGE ADDRESS | FM ORIGINATION PLAIN LANGUAGE ADDRESS | |
| 7 | TO TO ADDRESSEE RI AND PLAD | TO TO ADDRESSEE RI AND PLAD | TO TO ADDRESSEE RI AND PLAD | TO TO ADDRESSEE RI AND PLAD | |
| 8 | INFO INFORMATION ADDRESSEE 1 RI AND PLAD INFORMATION ADDRESSEE 2 RI AND PLAD | INFO INFORMATION ADDRESSEE 1 RI AND PLAD INFORMATION ADDRESSEE 2 RI AND PLAD | INFO INFORMATION ADDRESSEE 1 RI AND PLAD INFORMATION ADDRESSEE 2 RI AND PLAD | INFO INFORMATION ADDRESSEE 1 RI AND PLAD INFORMATION ADDRESSEE 2 RI AND PLAD | |
| 9 | |||||
| 10 | GROUP NO COUNT | ||||
| 11 | BREAK | BT | BT | BT | |
| 12 | UNCLASSIFIED THIS IS A TEST MESSAGE | UNCLAS THIS IS A TEST MESSAGE | UNCLAS THIS IS A TEST MESSAGE | UNCLAS THIS IS A TEST MESSAGE | |
| 13 | BREAK | BT | BT | BT | |
| 14 | |||||
| 15 | #0051 | ||||
| 16 | OVER | NNNN | NNNN | NNNN |
The concept of the standard message format originated in the wired telegraph services. Each telegraph company likely had its own format, but soon after radio telegraph services began, some elements of the message exchange format were codified in international conventions (such as Articles 9, 22, 26, 29, 30, and Appendix 1 of the International Radiotelegraph Convention, Washington, 1927), and these were then often duplicated in domestic radio communications regulations (such as the FCC in the U.S.) and in military procedure documentation.
Military organizations independently developed their own procedures, and in addition to differing from the international procedures, they sometimes differed between different branches of the military within the same country.
For example, the publication "Communication Instructions, 1929", [6] from the U.S. Navy Department, includes:
Technical Manuals
Field Manuals
Tables of Organization and Equipment (TOE)
Army Regulations
Forms
Training Material
And their modern decedents in the Allied Communications Procedures
Training for message handling may (or may not) be found listed in the following documents: