function irBack( frm, fvcode, operacion, id )
	{
		
		// Pop-up destino
		var width=750;
		var height=500;
		var left = (screen.width - width)  / 2;
	  	var top = (screen.height - height)  * 0.65;
		var features='top=' + top + ',left='+ left +',width='+ width +',height='+height+',resizable=1,scrollbars=1,status=1';
		//var features='width=750,height=500,resizable=1,scrollbars=1,status=1';
		var url = "/login_back.jsp?operacion="+ operacion;

		if( ( frm!= null ) && ( frm!= "" ) )
		{
			url+= "&pform="+ frm;
		}
		
		if( ( fvcode!= null ) && ( fvcode!= "" ) )
		{
			url+= "&fvcode='"+ fvcode+ "'";
		}
		
		if( ( id!= null ) && ( id!= "" ) )
		{
			url+= "&opid="+ id;
		}
		
		
		
		//alert( url );	
		window.open(url,"midestino",features);
	}