Internally, the plug-in imports and exports to the API clipboard. As part of the import and export process, the plug-in executes the copyKey or pasteKey MEL commands to transfer the anim curves from the API clipboard to the Maya objects. Using the plug-in will not change the contents of the Maya animation clipboard.
Import lets you set the same options as Edit > Keys > Paste Keys which are used when the animation is applied to the selected object(s).