In military munitions, a fuze is the part of the device that initiates function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The term fuze is used to indicate a sophisticated ignition device incorporating mechanical and/or electronic components e.g. a proximity fuze for an M107 artillery shell, magnetic/acoustic fuze on a sea mine, spring-loaded grenade fuze, pencil detonator or anti-handling device.Most[which?] English-language countries use the "z" spelling to distinguish between simple burning fuses and more complicated munition fuzes, which contain mechanical and/or electronic components, although historically this has by no means been a hard-and-fast rule, with "fuse" often used as the spelling in many sources, as the example "hand grenade fuse" shows.[citation needed] The relative complexity of even the earliest fuze designs (dating from circa 1915) can be seen in the cutaway diagrams at the end of this article. Modern fuzes for "smart weapons" are invariably computerised (i.e., incorporate microprocessors or gate arrays).