function getParam( aParamName ) {

	var queryString;
	var queryStringArray;
	var i;
	var paramArray;

	queryString = location.search.substring(1, location.search.length);
	queryStringArray = queryString.split('&');
	
	for(i=0;i<queryStringArray.length;i++) {
	
		paramArray = queryStringArray[i].split('=');
		
		if(paramArray[0]==aParamName) {
		
			// on a trouve notre parametre !
			return unescape(paramArray[1]);
		
		}
	
	}
	
	return '';//param non trouve : on renvoie chaine vide

}