[ model, action ]
here's how the following ognl would resolve:
[0] - a CompoundRoot object that contains our stack, [model, action]

[0].toString() - calls toString() on the first object in the value stack (excluding the CompoundRoot) that supports the toString() method

public class HomeAction implements Action {
    private String name= "propertyOfAction";
    private Person person=null;
    private Collection collection = new ArrayList();
    public String execute() throws Exception {
        collection.add(new Person("zkj"));
        collection.add(new Person("yql"));
        collection.add(person);
        return SUCCESS;
    }
    public String getName() {
        return name;
    }
    public Person getPerson() {
        return person;
    }
    public Collection getCollection() {
        return collection;
    }
    public void setPerson(Person person) {
        this.person = person;
    }
}

propertyOfAction

那么[0] [1] 有什么用呢,在循环中就体现出来了.

<ww:iterator value="collection" status="person">
            <ww:if test="#person.first == true"> 
                [0] :<ww:property value="[0]"/></br>
                [1] :<ww:property value="[1]"/></br>
                [2] :<ww:property value="[2]"/></br>
            </ww:if>
</ww:iterator>

[0] :[com.founder.Person@b3a5a0, com.founder.HomeAction@e3ffdf, com.opensymphony.xwork.DefaultTextProvider@d402dd]
[1] :[com.founder.HomeAction@e3ffdf, com.opensymphony.xwork.DefaultTextProvider@d402dd]
[2] :[com.opensymphony.xwork.DefaultTextProvider@d402dd]
输出以上代码,说明在一层循环中我们要访问[1]表示action对象.和没有循环的[0]对应.


总结:

假如你用webworkNOUI标签,对于Value Stack,一般你不要考虑[1] [0]之类的.记住一点
如果在循环中action的collection属性时体内,用[1]可以访问action对象和对应的属性.

对于多层循环或复杂用法,我只能告诉你,你的设计有问题?重构Model代码吧.