Apple, since the release of the Pro Keyboard, provides these last four keys on desktop keyboards above the numeric keypad where status indicator lights are on many IBM PC keyboards.
A Clear key, instead of a Num Lock key, on models with full numeric keypads, as these are dedicated to numeric input and not generally used for cursor control.
Compact keyboards such as the bluetooth wireless aluminium keyboard and the built-in keyboards on all Intel-based Macintosh notebooks range from F1-F12 only, just like IBM PC keyboards. F17-F19 keys were introduced with the aluminium USB keyboard.
Like the Shift and Control keys, the Option key serves as a modifier for the Command key shortcuts, as well as being used to type many special characters.