function acepta() {
accede=document.forms[0].length-1;
//alert(document.forms[0].length);
if (document.getElementById('usr_Accept').checked == true){
document.forms[0].elements[accede].disabled=false;
} else {
document.forms[0].elements[accede].disabled=true;
}
}

function validarForm(){
var completo=true;
	for (x=0;x!=document.forms[0].length;x++) {
	  if(document.forms[0].elements[x].getAttribute("oblg")==1){	
		if (document.forms[0].elements[x].value==""){
		    document.getElementById('imp').style.display = "block";
			completo=false;
			break;
		} else {
			completo=true;
		}
	  }
	}
	if(completo==true){
document.forms[0].submit();
}
}