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The Mystery of Manual Numbers

Military Manual Code Number Systems

To anyone who has looked at Military manuals the code number systems which they are arranged under is bewildering. This is especially true for anyone who is trying to understand and follow the changes in manuals over the last hundred years. What I hope to do in this short essay is try to clear up some of the confusion, to simplify the discussion we be will only be concerned with U.S.Army manuals and only the essential points of the coding systems will be covered.


From the beginning one code number prefix title has been used consistently. Army Regulations (ARs) which are concerned with the day by day running of the Army. Otherwise manual numbering systems have changed quite a bit. There are often many editions and changes to each manual number and there can be a great deal of difference between the manual editions. So manual FM 21-75 can have five editions covering 45 years of changes in doctrine. In reality each of the editions are more like five different manuals rather than one manual with a five series of changes.

Early Military Manuals

Until the 1890s there were no army manuals in the current sense. Military manuals before the 1890s were foreign imports or privately published manuals and textbooks, without any numbering. For all practical purposes they were simply books, with an author and title.

From the late 1880 until the end of First World War military manuals were either War Department Documents or Ordnance Department Documents. Both types of documents were numbered consecutively (1,2, 3, etc.) as they appeared with no variations concerning subject matter. But there was often a branch numbering system superimposed on the manual. For example War Department Document No.541 could also be Signal Manual No.3.

War Department Documents were approximately similar to modern Field Manuals with an occasional one concerned with a technical subject like signal communications and were usually hard covered books. Ordnance Department Documents were similar to modern Technical Manuals and could be either hard cover or paper backed.

After the First World War

Manuals began to be issued in loose leaf form designed to be placed in binders, numbering prefects including TR (Training Regulations), TM (Training Manuals), and TC (Training Circulars), with TRs being the most common type. There Prefixes were followed by a two to four digit number then a dash followed by a two to three digit number. Like TR 50-70 or TR 425-30. The first set of numbers noted the subject while the second set noted the number of the book under the subject. The subject number system was fairly complex. Unfortunately too complex for the length of this essay.

The Technical subjects of the earlier Ordnance Documents were incorporated into the Training regulation system.

The Late 1930S

The Training Regulations were merged into a series of branch Field Manuals, like Basic Field Manual, Cavalry Field Manual, etc. The Field Manuals of this period did not have a number system like current manuals. Instead FM 21-75 they are titled by subject like Basic Field Manual, Volume I, Chapter 3.

World War Two and After

The current U.S.Army manual number system was started at the beginning of the Second World War. The primarily types of manuals became either FMs (Field Manuals), or TMs (Technical Manuals), later followed by a bewildering arrangement of lesser Prefixes like TC (Training Circulars). ST (Special Texts), FC (Field Circulars), just to name a few.

Field Manuals were usually numbered by a one to two digit number followed by a dash followed by a one to two digit number, like FM 21-75, with the first series on numbers being the subject classification of the manual and the second series being the particular manual.

Technical Manuals were numbered at first like FMs, but because they were vastly more of them by the early 1960s, they began to be changed to a more complex system.

Early TMs have numbers like TM 9-2300. The first number being the subject or branch of the Army. Number 9 means that it is an Ordnance Branch manual. The second series of numbers referring to the particular manual.

The many later TMs, concerned with single pieces of equipment, especially Ordnance equipment, were numbered like TM 9-1005-223-12. The first number refers to the branch. The number 9 means that it is an Ordnance branch document. The second series of numbers refer to the subject type. The third series refers to the particular piece of equipment or subject. The four series on numbers refer to the level of maintenance which the manual is concerned with. With 10-12 being operator and organizational maintenance level, and with higher numbers concerned with a higher level, 20s being direct support, 30s being general support.

While this essay can only give the reader a brief snapshot of the coding system, I hope that it will clear up some confusion.

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