Look at this. Each triode is different and has different meanings.

1. China’s semiconductor device model naming method. Semiconductor device models consist of five parts (field effect devices, semiconductor special devices, composite tubes, PIN tubes, and laser devices only have the third, fourth, and fifth parts). )composition. The meanings of the five parts are as follows: Part 1: Use numbers to indicate the number of effective electrodes of the semiconductor device. 2-Diode, 3-Transistor Part 2: Use Chinese Pinyin letters to indicate the materials and polarity of semiconductor devices. When indicating diodes: A-N type germanium material, B-P type germanium material, C-N type silicon material, D-P type silicon material. When indicating a transistor: A-PNP type germanium material, B-NPN type germanium material, C-PNP type silicon material, D-NPN type silicon material. Part 3: Use Chinese pinyin letters to represent the internal type of semiconductor devices. P-ordinary tube, V-microwave tube, W-voltage regulator tube, C-parameter tube, Z-rectifier tube, L-rectifier stack, S-tunnel tube, N-damping tube, U-photoelectric device, K-switch tube , A-High-frequency high-power tube (fgt; 3MHz, Pcgt; 1W), T-semiconductor thyristor (controlled rectifier), Y-body effect device, B-avalanche tube, J-step recovery tube, CS-field effect tube , BT-semiconductor special devices, FH-composite tubes, PIN-PIN tubes, JG-laser devices. Part 4: Use numbers to express serial numbers. Part 5: Use Chinese pinyin letters to express specification numbers. For example: 3DG18 represents NPN silicon material high-frequency transistor 2. Japanese semiconductor discrete device model naming method. Semiconductor discrete devices produced in Japan, from five to seven Partially composed. Usually only the first five parts are used, and the symbol meanings of each part are as follows: Part 1: Use numbers to indicate the number or type of effective electrodes of the device. 0-Photoelectric (i.e. photosensitive) diode, triode and combination tube of the above devices, 1-diode, 2 triode or other devices with two pn junctions, 3-other devices with four effective electrodes or three pn junctions, ┄┄And so on. Part 2: Japan Electronics Industries Association JEIA registered mark. S- indicates semiconductor discrete devices registered with JEIA, the Japan Electronics Industry Association. Part 3: Use letters to indicate the polarity and type of materials used in the device. A-PNP type high frequency tube, B-PNP type low frequency tube, C-NPN type high frequency tube, D-NPN type low frequency tube, F-P control pole thyristor, G-N control pole thyristor, H-N base unijunction transistor , J-P channel field effect transistor, K-N channel field effect tube, M-triac. Part 4: Use numbers to indicate the serial number registered with the Japan Electronics Industry Association JEIA. An integer of more than two digits - starting from "11", indicating the serial number registered with the Japan Electronics Industry Association JEIA; devices with the same performance from different companies can use the same serial number; the larger the number, the more recent the product. Part 5: Use letters to indicate improved product marks of the same model. A, B, C, D, E, and F indicate that this device is an improved product of the original model. 3. The nomenclature of American semiconductor discrete device models. The nomenclature of American transistors or other semiconductor devices is confusing. The naming method of semiconductor discrete devices of the American Electronics Industry Association is as follows: Part 1: Use symbols to indicate the type of device use. JAN-military grade, JANTX-special military grade, JANTXV-super special military grade, JANS-aerospace grade, (none)-non-military supplies. Part 2: Use numbers to express the number of pn junctions. 1-diode, 2=transistor, 3-three pn junction devices, n-n pn junction devices. Part 3: Electronic Industries Association (EIA) registered mark. N-This device is registered with the Electronic Industries Association (EIA). Part 4: Electronic Industries Association registration sequence number. Multi-digit number - The serial number of the device registered with the Electronic Industries Association. Part 5: Use letters to indicate device classification.

A, B, C, D, ┄┄-different grades of the same type of device. For example: JAN2N3251A represents PNP silicon high-frequency low-power switching transistor, JAN-military grade, 2-transistor, N-EIA registration mark, 3251-EIA registration sequence number, A-2N3251A grade. 4. International Electronics Federation semiconductor device model naming method. European countries such as Germany, France, Italy, the Netherlands, and Belgium, as well as Eastern European countries such as Hungary, Romania, Yugoslavia, and Poland, mostly adopt the International Electronics Federation semiconductor discrete device model naming method. This naming method consists of four basic parts. The symbols and meanings of each part are as follows: Part 1: Use letters to indicate the materials used in the device. A-The band gap of the material used in the device is Eg=0.6~1.0eV, such as germanium, B-The Eg of the material used in the device is 1.0~1.3eV, such as silicon, C-The Eggt of the material used in the device; 1.3eV, such as gallium arsenide, D- Eglt of materials used in devices; 0.6eV such as indium antimonide, composite materials used in E-devices and materials used in photovoltaics Part 2: Use letters to indicate the type and main features of the device. A-detector switch mixing diode, B-varactor diode, C-low-frequency low-power transistor, D-low-frequency high-power transistor, E-tunnel diode, F-high-frequency low-power transistor, G-composite devices and other devices, H -Magnetic diode, K-Hall element in open magnetic circuit, L-high-frequency high-power transistor, M-Hall element in closed magnetic circuit, P-photosensitive device, Q-light-emitting device, R-low-power thyristor , S-low power switch tube, T-high power thyristor, U-high power switch tube, X-multiplier diode, Y-rectifier diode, Z-zener diode. Part 3: Use numbers or letters plus numbers to express the registration number. Three digits - represents the registration serial number of general-purpose semiconductor devices, and one letter plus two digits - represents the registration serial number of special-purpose semiconductor devices. Part 4: Use letters to classify devices of the same type. A, B, C, D, E┄┄-marks indicating that devices of the same model are classified according to a certain parameter. In addition to the four basic parts, suffixes are sometimes added to distinguish characteristics or further classify. Common suffixes are as follows: 1. The suffix of the Zener diode model. The first part of the suffix is ??a letter, indicating the allowable error range of the stable voltage value. The letters A, B, C, D, and E respectively indicate that the allowable error is ±1, ±2, ±5, ±10, and ±15; its suffix The second part is a number, which represents the integer value of the nominal stable voltage; the third part of the suffix is ??the letter V, which represents the decimal point. The number after the letter V is the decimal value of the nominal stable voltage of the voltage regulator tube. 2. The suffix of the rectifier diode is a number, which indicates the maximum reverse peak withstand voltage of the device, and the unit is volts. 3. The suffix of the thyristor model is also a number, which usually indicates the smaller value of the maximum reverse peak withstand voltage and the maximum reverse turn-off voltage. For example: BDX51-represents NPN silicon low-frequency high-power transistor, AF239S-represents PNP germanium high-frequency low-power transistor. 5. Early European semiconductor discrete device model nomenclature. Some European countries, such as Germany and the Netherlands, adopt the following naming method. Part 1: O-represents semiconductor device Part 2: A-diode, C-transistor, AP-photodiode, CP-phototransistor, AZ-voltage regulator, RP-optoelectronic device. Part 3: Multi-digit number - indicates the registration serial number of the device. Part 4: A, B, C┄┄-indicates variant products of the same type of device. Russia

Hope it helps.