There are two versions of the PowerBook 100's QWERTY layout keyboard: a domestic US version with 63 keys and an international ISO version with 64 keys. The caps lock key on the PowerBook 100 did not have a locking position or a lighted indicator of its status, and to compensate, the System 7 operating system software includes an extension file that causes an icon of the international caps lock symbol (⇪) to appear in the upper right-hand corner of the menu bar when Caps Lock is active.