通过AO裁剪图层?

通过各位大侠的指点,我知道通过IBASICGEOPROCESSOR接口可以裁剪图层,可是那个CLIP方法中,需要把裁剪的区域作为一个图层来处理.
现我有一个某城市的各区范围图,我就想用这个范围图中的某一个FEATURE来作为裁剪的范围,那怎么操作啊,我不知道ARCGIS帮助中这句话怎么来理解:The useSelectedInput state refers to whether or not a selected subset of the InputTable is to be clipped. True signifies that a selected subset will be clipped. False signifies that clip operation will ignore any selected subset.
请教各位,帮我解答一下,谢谢.