These are some of the most recognizable US WWII Aircraft designators:
B- designator used for bombers such as the B-17 "Flying Fortress"
C- designator used for transport aircraft such as the C-47 "Sky Train"
P- Pursuit (designator used for WWII era fighters, usually Army Air Corps) such as the P-51 "Mustang"
F- Designator used for US naval fighter aircraft such as the F6F "Hellcat" (later also adopted by Army Air Corp and still used by the US Navy, Marines and Air Force)
T- trainer such as the T-6 "Texan"
Some other countries used abbreviations of the manufacturer's name in their Designators like Germany:
ME-109, where "ME" is short for Messerschmitt. This same plane was also known as a BF-109 where "BF" stands for Bayerische Flugzeugwerke, as both companies had a contract to produce it.
HE as in "HE 111" was short for Heinkle. Also seen as "Heinkle He 111"
DO as in "DO 355" was short for Dornier. Also Seen as "Dornier Do 355"
FW as in FW-190 Was short for Focke Wulf
Since there are so many other planes and countries involved in WWII, this answer could go on forever. However, because this question was placed under "Military aircraft, SR-71 Blackbird" the WWII part of the question didn't really fit, so i will answer what the "SR" stands for: Surveillance and Reconnaissance.
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For example the M3 Half track was Model #3 in the series
For example: The M3 Half track meant Model #3 in the series In US there were serial numbers stenciled to vehicles In Germany white letters WH, WL, WK indicated Army:Wehrmacht Heer, Air force: Wehrmacht Luftwaffe and Navy: Wehrmacht Kriegsmarine stenciled on right rear of vehicle
Spain does not have initials. If you are asking about the letters mounted on the back of automobiles in Europe that are used to identify where the vehicle is licensed, the letter(s) used for Spain is black "E" on a white oval.
An employee's initials usually refer to the first letter of each part of their full name. For example, if an employee's name is John David Smith, his initials would be JDS. Initials are often used to identify individuals, especially in official documents or when signing paperwork.
Coalition markings, used to identify friendly vehicles visually to other coalition forces.
There are about 600 Million Motor Vehicles in the world.
Reference initials are typically used in business correspondence to indicate the person who prepared the document and the person who it is intended for, usually the signer. They are placed at the bottom of a letter or memo, with the preparer's initials followed by the initials of the individual who is signing the document. This helps clarify responsibility and accountability within an organization. Reference initials also serve as a quick way to identify who was involved in the communication process.
A stamp on jewelery is usually the jewelers stamp (initials of the jeweler). It is used to identify the manufacturer of the piece.
The initials for Arizona are AZ. All the states in the US have initials which are used as the abbreviation for a particular state.