var opera = (navigator.userAgent.indexOf('Opera') >= 0)? true : false;
	var ie = (document.all && !opera)? true : false;
	var dom = (document.getElementById && !ie && !opera)? true : false;
	var netsc = (navigator.userAgent.indexOf('Netscape') >= 0)? true : false;


	
	function changeTree(which) 
	{
	    if( treeOpen[current] )
		{
		   for (i in treeItems[current]) 
		     { removeElem(treeItems[current][i]); }	  
		   treeOpen[current] = false;
		   if( current == which )
		    return;		
		}
		
		if (treeOpen[which]) {
				for (i in treeItems[which]) 
				   removeElem(treeItems[which][i]);
				treeOpen[which] = false;
		} else {
				for (i in treeItems[which]) {
				putElem(treeItems[which][i]);
			}
		    treeOpen[which] = true;
			current = which;
		}
	}
	
	function OpenTree(which) 
	{
	   for (i in treeItems[which]) {
				putElem(treeItems[which][i]);
			}
		    treeOpen[which] = true;
			current = which;
	}
	
	function putElem(elemId) 
	  { getElem(elemId).style.display = "block"; }

	function removeElem(elemId) 
		{ getElem(elemId).style.display = "none"; }
	
	var current = 0;
	


function getElem(mId)
{
   if (ie) 
       return document.all[mId];
	else
	  return document.getElementById(mId);
}