function checkboxlist_verification(clientID, AlwaysRequired, MinNumberRequired, MaxNumberRequired)
{
    var col = document.getElementById(document.getElementById(clientID).controltovalidate).getElementsByTagName("input");

    if (col != null) {
        var checked = 0;
        var checkboxcount = 0;

        for (i = 0; i < col.length; i++ ) {

            var item = col[i];
            checkboxcount += 1;
            if (item.checked )
            {
                checked += 1;
            } 
        }

        if (checked >= MinNumberRequired && (checked <= MaxNumberRequired || MaxNumberRequired == 0))
        {
            return true;
        } 
        else if (checked == 0 && AlwaysRequired == false)
        {
            return true;
        } 
        else
        {
            return false;
        }
    }
}