Top cap, control cap, preload adjuster, etc... I don't know enough about suspension forks, but it seems the location and function of the control caps is not the same across the board.

Take a look at your fork and see if you can find the name and model number. It may be an SR Suntour, but you'll want the model number. From there, search for a schematic online where you can identify the small part number.

Or drop in at the local Giant dealer.