// get imgs
function findImg()
	{
	var imgs, i, anch, j, title;
	imgs = document.getElementsByTagName('img');
	anch = document.getElementsByTagName('a');
	for ( i = 0; i < imgs.length; i++ )
		{
// test for roll class
		if ( /roll/.test(imgs[i].className ))
			{
// assign behaviours
			imgs[i].onmouseover = function(){roll(this);};
			imgs[i].onmouseout = function(){roll(this);};
			}
		}
// get anchors
	for ( j = 0; j < anch.length; j++ )
		{
	// test for roll class
		if ( /roll/.test(anch[j].className ))
			{
	// assign behaviours
			anch[j].onmouseover = function(){roll(this);};
			anch[j].onmouseout = function(){roll(this);};
			}
		}
	}
	
// roll
function roll(o)
	{
	var src = o.src;
	var name = src.slice(0, src.lastIndexOf('_'));
	var ftype = src.substring(src.lastIndexOf('.'), src.length);
	if ( /_s1/.test(src))
		{
		var newsrc = src.replace('_s1','_s2');
		var hldr = document.getElementById( "holder" );
		var new_img_nm = name+ftype;
		var new_img = document.createElement( "img" );
		new_img.src = new_img_nm;
		new_img.alt = name;
		new_img.id = name;
		old_img = hldr.firstChild;
		hldr.replaceChild( new_img, old_img );
		}
		else
		{
		// else, back to off
		newsrc = src.replace('_s2','_s1');
		}
	o.src = newsrc;
	}

// onload trigger for rollovers
window.onload=function()
{
	findImg();
}