The structure of the keyboard layout file allows you to link several keys together so that they behave the same way. For example, it is often good to have the same behaviour for a letter key plus shift as for the same key plus caps lock, so that they always produce the same output, no matter what dead key state is active.

Sometimes, however, this linking is not what you want. If you get unexpected results from modifying one key, in that it causes a change in that key with a different combination of modifiers, then you can unlink that key and modifier combination. Just choose “Unlink Key...” from the Keyboard menu, and specify the key and modifier combination, whether directly (pressing the key on the keyboard or clicking the key in the window) or by key code.