function Soumettre(action){
	param="";
	switch (action){
                case "AffichHisto":
			param=param+"&inst="+top.inst_en_cour;
		break;

        }
	if (param.length!=0){
		envoi('POST','rpc.php',param,action);
	}
}

<?
header('Content-type: text/html; charset=iso-8859-1'); 
switch($action){
	case "AffichHisto":
	require "./actionBD/afficheHisto.php";
	break;
}
?>

<?
$requeteEtape="	SELECT `date_cloture`, `sig_etape_sig_procedure_id_procedure`, `sig_etape_id_etape`, `id_instance_etape` FROM `sig_instance_etape` WHERE `sig_inst_procedure_id_inst_procedure` LIKE $inst AND `date_instanciation` IS NOT NULL";
$resultEtape=ExecRequete($requeteEtape, $connect);
while($ligne_req_etape=mysql_fetch_array($resultEtape)){
	$reqEtape="SELECT `commentaire`, `Num_etape` FROM `sig_etape` WHERE `id_etape` LIKE $ligne_req_etape[sig_etape_id_etape]";
	$resultreq=ExecRequete($reqEtape, $connect);
	$ligne_etape=mysql_fetch_array($resultreq);
	echo "AjoutEtape(\"$ligne_etape[commentaire]\",\"$ligne_etape[Num_etape]\",\"$ligne_req_etape[id_instance_etape]\");";
}
?>

function envoi(mode,url,params,destination) {
	var http_request = false;
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		http_request = new XMLHttpRequest();
	} else if (window.ActiveXObject) { // IE
		try {
			http_request = new ActiveXObject("Msxml2.XMLHTTP");
		}catch (e){
			try{
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			}catch (e) {
			}
		}
	}
	if (!http_request) {
		alert('Abandon :( Impossible de créer une instance XMLHTTP');
		return false;
	}
	http_request.onreadystatechange = function() { lecture(http_request); };
	http_request.open(mode, url, true);
	http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	var data='action='+destination+params;
	http_request.send(data);
}

function lecture(http_request) {
	if (http_request.readyState == 4) {
		if (http_request.status == 200) {//alert (http_request.responseText);
			eval(http_request.responseText);
		} else {
			alert('Un problème est survenu avec la requête.');
		}
	}
}