Miscellaneous Designation Systems

Copyright © 2000-2024 Andreas Parsch

1 Army Nomenclature System

2 Navy MARK/MOD Nomenclature System

3 Joint Photographic Type Designation System

4 Telecommunications Security (TSEC) Nomenclature System

5 Joint Optical Range Instrumentation Type Designation System

This article explains designation systems, which are not specific to military aviation related equipment, but which are nevertheless regularly encountered when studying the subject.

1 Army Nomenclature System

The Army designates most types of equipment in accordance with the Army Nomenclature System (formerly known as Ordnance Nomenclature System) as defined in MIL-STD-1464A. These type designators are generally known as "Ordnance Numbers" or "M"-numbers. A designation is usually assigned as soon as a new equipment item enters the Army inventory. The numerical type designators are not "globally" unique, but only within a certain category of equipment, like tanks, armoured vehicles, guns, etc. Therefore, the full designation for an item designated within this system must always include an item name.

Examples: GUIDED MISSILE, SURFACE-TO-AIR: XM 3 E1
MAIN BATTLE TANK: M 1 A1
CANNON, 20MM: XM 301
PROJECTILE, 155MM: M 547 A2E1
(1) (3) (2) (4)

(1) is the name of the item, which is part of the complete nomenclature. According to MIL-STD-1464A, the name must be written in capital letters, and is to be followed by a colon. The name should be selected from DoD Cataloging Handbook H6 ("Federal Item Name Directory").

Number (2) is an arbitrary number. The numbers are usually assigned in numerical sequence within each equipment category. Since the latest change of MIL-STD-1464A, dated 17 February 2023, the sequential assignment is no longer specified in the regulations. Now the number has only to be unique within the numbers of currently fielded items of each equipment category. This allows for skipping of numbers, as well as reuse of older numbers which are no longer in use.

Two different prefixes (3) are used:

(4) is an optional letter/number suffix used to denote modifications of the equipment. Two different letters are used:

Modifications of service equipment use the suffixes A1, A2, etc., while experimental modifications use suffixes E1, E2, etc. These suffixes can be combined, e.g. M547A2E1 would be the first experimental modification of the second modification (i.e. third version) of the M547 item. If the M547A2E1 would be accepted as a standard service item, the designation would change to M547A3.

Note: According to MIL-STD-1464A, dashes or spaces must not be used in Army Nomenclature numerical designators. E.g., only M1A1 is correct nomenclature, while variants like M-1A1 or M1-A1 are incorrect.

Historical Information

The U.S. Army assigned model numbers with an M prefix to some type of equipment (e.g. rifles) almost since its inception. But the numbers in these early designations were always the year, in which the equipment was fielded. Other equipment (e.g. artillery projectiles) was designated with "Mark" (MK.) and a roman numeral. In July 1925, all these designation systems were replaced by the curent one, where M numbers are assigned sequencially form 1 up, separately for every category of equipment.

In the original form of the designation system, equipment, which was tested or evaluated, received designations with a T prefix (possibly standing for "Trial" or "Test") instead of M, followed by a consecutive number for each category. When becoming standard equipment, the T number was replaced by the next available M number in the respective equipment series. At some time in the 1950s, this system was gradually changed to the current one, where experimental or test items receive XM prefixes, with the number already in the proper M sequence. This has the advantage, that only the prefix, but not the number, changes, when the equipment is standardized.

Numerical Listings

Bombs
Rockets
Cartridges & Projectiles

2 Navy MARK/MOD Nomenclature System

The Navy assignes MARK/MOD numbers to nearly all types of equipment not covered by other designation systems, e.g. torpedoes, mines, guns, missile launchers, etc. This MARK/MOD system has its origins in the early 20th century, and was formally adopted in 1944. Of course, it was revised and extended over time, and the current standard is defined in MIL-STD-1661.

Similar in concept to the Army Nomenclature System, the full nomenclature for an equipment item consists of a type name and the MARK/MOD numbers. Examples are:

Examples: Torpedo, MARK 46 MOD 4
Fire Control System, Missile, MARK 99 MOD 0
Mount, Gun, 8 Inch, MARK 225 MOD 1
Launcher, Missile, EX 31 MOD 0
(1) (2) (3)

(1) is the name of the item, which is part of the complete nomenclature. According to MIL-STD-1661, the name is to precede the MARK number, and separated from the latter by a comma. The name should be selected from DoD Cataloging Handbook H6 ("Federal Item Name Directory"). In tabulated equipment listings, the item names should be written in "inverted nomenclature", in which the usual order of words in the name is reversed (as in the list of examples). That way, related items will be grouped together in alphabetical listings.

Number (2) is the MARK number. MARK numbers are assigned in numerical sequence within each equipment category. The prefix EX instead of MARK is used for experimental or developmental items. If an EX item is adopted for operational use, it will use MARK afterwards, but will keep the assigned number.

Number (3) is the MOD number, which indicates a modification or variant of the equipment. MOD numbers are assigned in numerical sequence for each equipment, the initial version being designated MOD 0. When an item is redesignated from EX to MARK, the MOD numbers for "MARK" are restarted from Zero. An example will clarify this: An experimental item is designated EX 44, and the MOD numbers 0 through 5 were assigned during development. Now it is decided to put MOD 1 and MOD 5 into operational service. Then EX 44 MOD 1 would be redesignated MARK 44 MOD 0, and EX 44 MOD 5 would become MARK 44 MOD 1. However, if all (or nearly all) MODs of the EX series are to become operational, the MOD numbers can be retained for the MARK series, the (few) unused numbers being left unassinged in the MARK series.

The general guideline is to write the words MARK and MOD unabbreviated and in uppercase. However, abbreviation of MARK as MK and/or use of mixed-case (Mark/Mod) lettering is explicitly allowed. Dashes and other punctuations should not be used. Therefore, all the following variants are correct nomenclature:

Torpedo, MARK 46 MOD 4
Torpedo, MK 46 MOD 4
Torpedo, Mark 46 Mod 4
Torpedo, Mk 46 Mod 4

The following variants do not conform to the strict rules of MIL-STD-1661, but are nevertheless quite common:

Torpedo, Mark-46 Mod 4
Torpedo, MK-46 Mod 4
Torpedo, Mk.46 Mod 4

Numerical Listings

Bombs
Cluster Bombs
Torpedoes

3 Joint Photographic Type Designation System

The Joint Photographic Type Designation System was originally defined in MIL-STD-155, and has been absorbed into the current MIL-STD-1812 on 28 February 1991. Designations are assigned to conventional film type photographic equipment. Excluded is electro-optical and other imaging equipment designated in the Joint Electronics Type Designation System.

Examples: K S - 87 B
K A - 93 A 4
(1) (2) (3) (4) (5)

Letter (1) designates the equipment category:

Letter (2) designates the purpose of the equipment:

(3) is the model number. Each two-letter Category-Purpose combination uses its own model number sequence, starting at 1. Two blocks of high model numbers (500-599, 2500-2599) are reserved for use by Canada. Most likely the first number of the Canadian block (500) is never used, i.e. Canadian designations probably always start with 501.

Letter (4) designates a modification of the equipment. The first production model will receive letter "A", the second "B", etc. Letters "I" and "O" are not used.

(5) is an optional suffix number for minor modifications.

Designation Listings

For equipment designators shown in light gray without a link, I haven't found any designations so far.

Picture Using Equipment

Picture Processing Equipment

Cameras

4 Telecommunications Security (TSEC) Nomenclature System

Most cryptographic and COMSEC equipment used by the US military and civilian intelligence agencies is designated in the Telecommunications Security (TSEC) nomenclature. The nomenclature for equipment systems, items and assemblies (i.e. components) is slightly different.

Examples for Items and Systems: TSEC / K Y - 57
TSEC / K G - 84 C
TSEC / H N - 74
TSEC / C Y - 104 A
TSEC / C I - 10
Examples for Assemblies: K Y X - 15 A / TSEC
H G F - 96 / TSEC
(1) (2) (3) (4) (5)

Designators for items and systems are always prefixed by "TSEC/", while designations for assemblies use a "/TSEC" suffix. However, assembly designations are sometimes incorrectly quoted with a "TSEC/" prefix.

Letter (1) is the function of the equipment:

Letter (2) is the type or purpose of the equipment:

Letter (3) is only used for designations of assemblies and designates the type or purpose of the assembly:

(4) is a model number. Each letter combination uses its own sequentially assigned model number series.

The optional suffix letter (5) denotes a specific version of the equipment. The first version uses no suffix, the first modifcation uses "A", etc.

5 Joint Optical Range Instrumentation Type Designation System

You never heard of this one? Well, neither did I until I stumbled across it during the research for this site. It is probably completely irrelevant to military aviation and I don't know any designations, but it's included for the fun of it ;-)!

The system was introduced on 04 December 1964 in MIL-STD-787. Obviously, someone thought that optical range instrumentation equipment should receive rationalized designations (the early 60's were high time for joint designation systems!). MIL-STD-787 was finally cancelled on 05 December 1995 - maybe because nobody used the system ;-)!

The designation system followed the general lines of the Joint Electronics Type Designation System and distinguished between end items and components.
End Items were designated as follows:

Example: ORI / C B C - 4 A
(1) (2) (3) (4) (5)

All designations were prefixed by "ORI/", which stood for "Optical Range Instrumentation".

Letter (1) indicated the type of of the equipment:

Letter (2) indicated the characteristics of the equipment:

Letter (3) indicated the installation location of the equipment:

(4) is the model number. Each Type-Characteristics-Installation letter combination used its own model number sequence, starting at 1.

The optional suffix letter (5) denoted a specific version of the equipment. The first version used no suffix, the first modifcation used "A", etc.

Parts and components of equipment items were designated as follows:

Example: TT - 5 / DCB-2
TT - 1 A / CBC
(1) (2) (3) (4)

The two-letter code (1) indicated the type of component:

(2) is the model number. Each type indicator used its own model number sequence, starting at 1.

The optional suffix letter (3) denoted a specific version of the equipment. The first version used no suffix, the first modifcation used "A", etc.

(4) The full type designation of a component included a slant bar, followed by the designation of the item, of which it is a part. If the component can be used with several systems, a more general designator is appended. E.g. the TT-1A/CDC is a tracker's telescope, which is used with several ORI/CBC-n items.




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Last Updated: 16 September 2024