The keys that are not ordinary output keys are referred to as special keys. These include return, enter, the arrow keys, tab, delete, backspace, page up, page down, home, end, escape, the function keys F1-F20, help, clear, and a few others. These do not produce normal output, but exercise control functions, and have specific required outputs.

Many keyboard layouts, including those generated through some of the automatic conversion tools, are missing the output for some of these special keys. In part, this is because Apple has introduced more function keys on their keyboards, and older keyboard layouts do not have the output for the extra function keys.

When you open a keyboard layout that is missing some special key output, Ukelele asks if you want to add it. If you do not do so at this point, you can always add it by choosing “Add Special Key Output” from the Keyboard menu. This will not alter any output that you have already assigned, but will only add output for those special keys that do not have any output defined.