ifIsFirstIteration 
Includes its body if the current node is the first node in the current iteration. For example, when displaying a list of first-level nodes in a top-level navigation iView, use this tag if you need to display the first node differently from all other nodes.
The tag must be nested in one of the following tags:
iterateInitialNavNodes
iterateNavNodeChildren
iterateNavNodesInSelectedPath
iterateRelatedNavNodes
iterateSelectedNavNodesLevel
recurseNavNodeChildren
The following displays different markup if it is the first iteration pass.
Syntax
<ul id="tln">
<nav:iterateInitialNavNodes>
<nav:ifIsFirstIteration>
<li class="first">
</nav:ifIsFirstIteration>
<nav:ifNotIsFirstIteration>
<li>
</nav:ifNotIsFirstIteration>
<nav:navNodeAnchor navigationMethod="byURL"/>
</li>
</nav:iterateInitialNavNodes>
</ul>