Editing Transistor (section)

===Proprietary===
Manufacturers of devices may have their proprietary numbering system, for example [[CK722]]. Since devices are [[Second source|second-sourced]], a manufacturer's prefix (like MPF in MPF102, which originally would denote a [[Motorola]] [[FET]]) now is an unreliable indicator of who made the device. Some proprietary naming schemes adopt parts of other naming schemes, for example, a PN2222A is a (possibly [[Fairchild Semiconductor]]) 2N2222A in a plastic case (but a PN108 is a plastic version of a BC108, not a 2N108, while the PN100 is unrelated to other xx100 devices).

Military part numbers sometimes are assigned their codes, such as the [[UK CV series|British Military CV Naming System]].

Manufacturers buying large numbers of similar parts may have them supplied with ''house numbers'', identifying a particular purchasing specification and not necessarily a device with a standardized registered number. For example, an HP part 1854,0053 is a (JEDEC) 2N2218 transistor<ref>{{cite web |url=http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |title=Richard Freeman's HP Part numbers Crossreference |publisher=Hpmuseum.org |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120605183505/http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |archive-date=June 5, 2012 }}</ref><ref>{{cite web |url=http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |title=Transistor–Diode Cross Reference – H.P. Part Numbers to JEDEC (pdf) |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160508135527/http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |archive-date=May 8, 2016 }}</ref> which is also assigned the CV number: CV7763<ref>{{cite web |url=http://www.qsl.net/g8yoa/cv_table.html |title=CV Device Cross-reference by Andy Lake |publisher=Qsl.net |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120121111531/http://www.qsl.net/g8yoa/cv_table.html |archive-date=January 21, 2012 }}</ref>