What does the clear key do on Apple's numpad?

Apple has a keyboard with a numpad. What does the clear key on the top left of the numpad do? Is it different from the delete key, if so, how is it different?

The standard OS X behaviour is for it to act similar to a delete key, but only when text is selected. It won't delete forwards or backwards like the standard delete keys. It also acts as a standard clear button in the Calculator app. This can vary by app however - in Excel for example, it functions identically to the backspace key.

I just found out by accident that it is also equivalent to clicking the cancel button on dialogs.