// 
// Function to hide or display a block.
// Optionally, show an expand/contract plus-minus graphic
// event_id is the HTML element to be hidden or displayed
// oImage is the HTML IMG element to switch the image for
// Current use switches between add_small.gif and minus_small.gif
// BE SURE TO define the VARs for the images before using
// E.G. var minusimg = new Image().src='path to the image'
//      var plusimg = new Image().src='path to image'
//
function toggle(event_id,oImage)
{
        var el, bWhich;
        if (el = document.getElementById(event_id))
        {
                bWhich = (el.style.display != 'block');
                el.style.display = bWhich ? 'block' : 'none';
               if(oImage != null){ 
               oImage.src = bWhich ? minusimg : plusimg;   
               }             
                
        }
}