getting the xml child name via php/DOM

[jo1991]

 <doc>

          <y>

            <list_type>1</list_type>

            <libel> lible 1</libel>

       

          </y>

          <x>

            <list_type>6</list_type>

            <libel> lible 2</libel>

           

          </x>

          <y>

            <list_type>3</list_type>

            <libel> lible 3</libel>

     

          </y>

 </doc>

 

hi all,

this is an extract of my big xml file. <doc> is not the root of the document, its one of the root's childs, and also it's not the first child. the question here: 

how i can get the name of each child of the node <doc>?

how i can also get all the value of each child?