function selectAll(form_obj, name)
{ 
    for(var i = 0; i < form_obj.elements.length; i++)
    {
        var elem = form_obj.elements[i];
        if(elem.type == 'checkbox' && elem.name == name)
        {
            elem.checked = true;
        }
    }
    return;
}
function selectNone(form_obj, name)
{
    for(var i = 0; i < form_obj.elements.length; i++)
    {
        var elem = form_obj.elements[i];
        if(elem.type == 'checkbox' && elem.name == name)
        {
            elem.checked = false;
        }
    }
    return;
}
function selectInverse(form_obj, name)
{
    for(var i = 0; i < form_obj.elements.length; i++)
    {
        var elem = form_obj.elements[i];
        if(elem.type == 'checkbox' && elem.name == name)
        {
            elem.checked = elem.checked ? false: true;
        }
    }
    return;
}