A well-known class of IBM PC keyboards is the Model M. Introduced in 1984 and manufactured by IBM, Lexmark, Maxi-Switch and Unicomp, the vast majority of Model M keyboards feature a buckling spring key design and many have fully swappable keycaps.
Common additions to the standard layouts include additional power management keys, volume controls, media player controls (e.g. "Play/Pause", "Previous track", "Next track") and miscellaneous user-configurable shortcuts for email client, World Wide Web browser, etc.
[8] The magazine reported in 1982 that it received more letters to its "Wish List" column asking for the ability to determine the status of the three lock keys than on any other topic.
[12] "I wasn't thrilled with the placement of [the left Shift and Return] keys, either", IBM's Don Estridge stated in 1983.
Some of the additions have been inspired by the opportunity or requirement for improving user productivity with general office application software, while other slightly more general keyboard additions have become the factory standards after being introduced by certain operating system or GUI software vendors such as Microsoft.