The big button is the Power/Reset button. From
Wikipedia:
Most of the original ADB Apple Macintosh keyboards, as well as the first USB keyboard, had a key to turn the machine on in lieu of a physical power button on the computer itself. The symbol on it was usually a triangle pointing left (◁). On most keyboards it was located at the extreme upper-right corner, above the function keys and above the right most key, or in the same vertical position and in the center. The power button was replaced with a disc eject button when the Apple Pro Keyboard was introduced, and Apple removed the ability of Macs to be switched on from the keyboard. Pressing the power button when running Mac OS brought up the shutdown dialog box, on keyboards with an eject button the combination Control-Eject is used instead (for most x-Power keyboard combinations, x-Eject is used as the replacement combination).
The AEK and AEKII have their Power buttons on the upper right corner, to the right of the keyboard LEDs.
Is the M0118 like the M0116, only with a slightly different layout?