Keyboard shortcuts are useful options for quickly accessing specific program commands or system services, such holding the Command key and pressing C, X, or V, for copy, cut, and paste.
While common and useful commands are usually assigned a hot-key shortcut, you can also set up custom hot-key assignments in an application to give unassigned commands a hot key to invoke that command.
To do this, simply go to the "Shortcuts" tab in the Keyboard pane of System Preferences, and choose "App Shortcuts" in the categories list, where you can click the plus button to add a custom shortcut. Now select a desired application, or choose "All Applications" for a global shortcut. Type the exact name of the command you are trying to invoke (such as "Zoom" for the global option to resize windows, similar to clicking the green zoom button in most windows), and then enter a desired hot-key sequence to invoke this command.
This feature can be exceptionally useful in OS X, and usually only requires you to type the command as-is; however, there may be some instances where two commands are the same. For instance, you might have an image viewing or editing application that has its own "Zoom" command, which you might like to assign separately.
Even if you do not want to assign a separate hot key, the system may trigger the wrong one when that application is open, and instead of zooming into the document window as desired, your assigned hot key may invoke the program's image zooming feature (overriding any built-in hot keys for the command, if present).
To overcome this confusion, you can specify which command is to be used by including a full path designation to it. When you enter a command name for a hot key, OS X will simply search the menus for the first instance of that command, but by designating a full path to the command, you can override this search and the desired command will be chosen every time.
To do this, simply use "->" arrows in the following manner, to specify a menu and its contained items and submenus:
With these path designations, there is no possibility that "Zoom" or "Outline" will be chosen from an alternate menu command of the same name.