What key is the equivalent to this one?

Question

Is there an equivalent alternative to the key that looks like a square with little round snips outside of each corner (what is it called?), that can be found down to the left on some keyboards (I think Mac keyboards)?
This key has a good use in the notation program Finale. I don't find it on most keyboards, only on some. What key or key combination can be used instead, on those keyboards that don't have this key?

Answer 1

Do you use Finale on Windows or OS X? Here's why I asked:

It is only found on Mac keyboards and is called the "Command Key". If you use a Windows keyboard on a MAC (Works like a charm!) use the "Windows Key" instead.

If you use Windows, the key is MAC OS X ONLY and you can't use it.

Answer 2

its the Ctrl key