function validaruk()
 {
	var men="";
	if (document.forms[0].elements[0].value.length==0)
	 {
		men=men+"\tName\n";
	 }
	if (document.forms[0].elements[2].value.length==0)
	 {
		men=men+"\tSubject\n";
	 }
	if (document.forms[0].elements[4].value.length==0)
	 {
		men=men+"\tEmail\n";
	 }
	if (document.forms[0].elements[5].value.length==0)
	 {
		men=men+"\tMessage\n";
	 }
	if (men)
	 {
		alert("You have to complete the following data:\n\n"+men);
		valor=false;
	 }
	else
	 {
		var i = 1;
        var s = document.forms[0].elements[3].value;
		var sLength = document.forms[0].elements[3].value.length;
   		while ((i < sLength) && (s.charAt(i) != "@"))
  	     { i++
    	 }
		if ((i >= sLength) || (s.charAt(i) != "@")) men = "You have to write a valid e-mail address";
		else i += 2;
		while ((i < sLength) && (s.charAt(i) != "."))
		 { i++
         }
	   	if ((i >= sLength - 1) || (s.charAt(i) != ".")) men = "You have to write a valid e-mail address";
		if (men)
		 {
			alert(men);
			valor=false;
		 }
		else
		 {
			valor=true;
		 }
	 }
	return(valor);
 }

function ventana(cad,ancho,alto)
 {
	id=window.open(cad,"","width="+ancho+",height="+alto+",left=20,top=20,scrollbars=1");
 }

function busca()
 {
	var mens="";
	var valor=true;
	if (document.forms[0].elements[0].value.length>0) {mens=valalfanumerico(document.forms[0].elements[0].value);}
	if (document.forms[0].elements[1].value.length>0) {mens+=valalfanumerico(document.forms[0].elements[1].value);}
	if (document.forms[0].elements[2].value.length>0) {mens+=valalfanumerico(document.forms[0].elements[2].value);}
	if (document.forms[0].elements[3].options[document.forms[0].elements[3].selectedIndex].value.length>0) {mens+=valalfanumerico(document.forms[0].elements[3].options[document.forms[0].elements[3].selectedIndex].value);}
	if (mens)
	{
		window.alert(mens);
		valor=false;
	}
	return(valor);
 }

function valalfanumerico(cadena)
 {	
	carac=new String("");
	num=new String("");
	men=""
	cadval=new String("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");
	num=cadena.toUpperCase();
	longitud=num.length;
	carac="";
	for (i=0;i<longitud;i++) if(!(cadval.indexOf(num.charAt(i))+1)) carac=carac+num.charAt(i);
	if (carac) men="Invalid: "+carac+"";
	return(men);
 }