Editing Pro Electron (section)

===Suffixes and version specifiers===
Suffixes may be used, letters or perhaps blocks of digits delimited by "/" or "-" from the serial number, often without fixed meanings but some of the more common conventions are:
* for small-signal transistors "A" to "C" often means low to high h<sub>FE</sub>, such as in: BC549C<ref>[http://www.fairchildsemi.com/ds/BC/BC549.pdf Datasheet for BC549, with A,B and C gain groupings]</ref>),
* numeric suffixes may be used as an alternative way to show h<sub>FE</sub> (e.g. BC327-25), or voltage rating (e.g. BUK854-800A<ref>[http://www.datasheetcatalog.org/datasheet/philips/BUK854-800A.pdf datasheet for BUK854-800A (800 volt IGBT)]</ref>).
* for voltage reference diodes letters show the tolerance ("A","B","C","D","E" indicate 1%/2%/5%/10*/20%) and may be followed by the V<sub>z</sub> value, e.g. 6V8 for 6.8 Volts or 18V for 18 volts.
* "R" can mean "reverse polarity".

Examples of suffixes and manufacturers' extensions to the basic sequence number include:

{|class="wikitable"
|-
! Prefix class !! Usage  !! Example || Notes
|-
|AC||[[Germanium]] small signal transistor || AC127/01 || an AC127 (TO-1 case) with built-on heat-conducting block
|-
|AF||[[Germanium]] [[Radio Frequency|RF]] transistor || AFY40R || the "Y40" sequence number implies industrial uses, <br />the "R" indicates reduced specifications
|-
|BC||Silicon, small-signal transistor ("allround" or "G.P.") || BC183LB || the "L" indicates Base-Collector-Emitter pinout while <br />the "B" suffix indicates medium gain (240-500 h<sub>FE</sub>) selection
|-
|BC||Silicon, small-signal transistor || BC337-25 || -25 indicates an h<sub>FE</sub> of around 250 (140-400 range)
|-
|BD||Silicon Darlington-pair power transistor || BDT60B || the "B" suffix here indicates medium voltage (-100V<sub>CBO</sub>)
|-
|BF||Silicon [[Radio Frequency|RF]] (high-frequency) [[BJT]] or [[FET]] || BF493S || a BF493 with a -350V<sub>CEO</sub> rating
|-
|BL||Silicon high-frequency, high-power (for transmitters) || BLY49A || BLY49 in a TO-66 case
|-
|BS||Silicon switching transistor, bipolar or [[MOSFET]] || BSV52LT1 || SOT-23 (surface-mount) package
|-
|BT||Silicon Thyristor or TRIAC || BT138/800 || 800V-rated TRIAC
|-
|BU||Silicon high-voltage (for [[Cathode-ray tube|CRT]] horizontal deflection circuits) || BU508D || a BU508 with integral damper diode
|-
|BZ||Silicon regulator ("Zener") diode || BZY88-C5V6 || "C" indicates 5% tolerance, "5V6" indicates 5.6V<sub>z</sub>
|}

Note: A BC546 might only be marked "C546" by some manufacturers, thus possibly creating confusion with JIS abbreviated markings, because a transistor marked "C546" might also be a 2SC546.

Short summary of the most common semiconductor diode and transistor designations:
       BC549C
      / |--- \___ variant (A,B,C for transistors implies low, medium or high gain)
     /  |   \____ serial number (at least 3 digits or letter and 2 digits)
    /  device type:
 A=Ge     A=Signal diode
 B=Si     C=LF low-power transistor
          D=LF Power transistor
          F=RF transistor (or FET) 
          P=Photosensitive transistor etc.
          T=Triac or thyristor
          Y=Rectifier diode
          Z=Zener diode