tvns:treeview 树控件

[风之独韵]

能否说说这样的树控件的执行流程（是从上往下执行的？），还有这些属性用途？
<tvns:treeview
oncontextmenu="return false;"
childType="enabled"
onnodeclick="nodeclick(this,event.treeNode);"
selectedNodeIndex="0"
HelperID="___ctl0_State__"
systemImagesPath="/images/treeimages/"
onexpand="tree_expand(this);"
oncollapse="tree_collapse(this);"
oncheck="tree_check(this);"
onselectedindexchange="tree_selectedchange(this);">
<tvns:treenodetype Type="enabled" defaultStyle="color:blue;" ImageUrl="/images/icons/org.gif" ExpandedImageUrl="/images/icons/org.gif">
</tvns:treenodetype>
<tvns:treenodetype Type="disabled" defaultStyle="color:gray;" ImageUrl="/images/icons/org1.gif" ExpandedImageUrl="/images/icons/org1.gif">
</tvns:treenodetype>
<logic:present name="treeview" scope="request">
<% TreeNode root = (TreeNode)request.getAttribute("treeview");
root.outputXML("",0,pageContext.getOut(),"tvns:treenode"); %>
</logic:present>
</tvns:treeview>