htmlCabecalho = '<table width="100%" border="0" cellspacing="0" cellpadding="0">';
htmlCabecalho += '	<tr>';
htmlCabecalho += '		<td height="12" colspan="2" bgcolor="#fbf8e7">';
htmlCabecalho += '			<img src="/acmcarga/imagens/layout/top_barra.jpg" width="780" height="12" />';
htmlCabecalho += '		</td>';
htmlCabecalho += '	</tr>';
htmlCabecalho += '	<tr>';
htmlCabecalho += '		<td height="2" colspan="2" bgcolor="#BBA76A">';
htmlCabecalho += '		</td>';
htmlCabecalho += '	</tr>';
htmlCabecalho += '	<tr>';
htmlCabecalho += '		<td width="123" height="76" background="/acmcarga/imagens/layout/top_fundo.jpg">';
htmlCabecalho += '			<img src="/acmcarga/imagens/layout/logo_mrs.jpg" alt="" width="123" height="76" />';
htmlCabecalho += '		</td>';
htmlCabecalho += '		<td align="right" background="/acmcarga/imagens/layout/top_fundo.jpg">';
htmlCabecalho += '			<img src="/acmcarga/imagens/layout/top_ilustra.jpg" width="657" height="76" />';
htmlCabecalho += '		</td>';
htmlCabecalho += '	</tr>';
htmlCabecalho += '</table>';

function validaBackspace(e){
    if (!e) var e = window.event;
    var unicode=e.charCode? e.charCode : e.keyCode;
    if (unicode==8){
        var target = e.target ? e.target : e.srcElement;
        if (target.type!="text" && target.type!="textarea" && target.type!="password"){
            return false;
        } else {
            e.cancelBubble = true;
        }
    }
}
document.onkeydown=validaBackspace;
//document.oncontextmenu = function(){return false};