struts action-mapping中的input的作用

<action path="/somepath" 
        type="SomeAction" 
        name="SomeForm" 
        scope="session"

        input="someinput.jsp">

If the form bean SomeForm returns validation errors , it will return the page someinput.jsp.
input attribute is required if "name" is specified and the input bean returns validation errors. It is optional if "name" is specified and the input bean does not return validation errors.