function RegisterHiddenValue(key,value) {
    
    var hidden = document.getElementById(key);
    if( !hidden ) {
        hidden = document.createElement('INPUT');
        hidden.type = 'hidden';
        hidden.id = key;
        hidden.name = key;
        document.forms[0].appendChild(hidden);    
    }
    hidden.value = value;
    return hidden;
}