function validEmail(d){
	if (d.value == "") {
	  alert("Please enter your email address.")
	  d.focus()
	  return false
	}
	var EmailRegExp = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9])+$/;
	if (!EmailRegExp.test(d.value)) {
	  window.alert("Your e-mail address is wrong. Please try again.");
	  d.focus();
	  return false;
	}
	return true;
}

function isDiggit(c) {
	var test = "" + c ;   
	if ( test=="0" ||  test=="1" ||  test=="2" ||  test=="3" ||  test=="4" ||  test=="5" ||  test=="6" ||  test=="7" ||  test=="8" ||  test=="9" ||  test==" ") return true;
	return false; 
}

function hasPermittedLetters(s) {
	var sn=s.length;
	for (var k=0;k<sn;k++) 
	  if(!isDiggit(s.substring(k,k+1))) return false;
	return true;
}

function v() {
	if (!document.f.name.value) {
	  window.alert("Your name?");
	  document.f.name.select();
	  document.f.name.focus(); return false; } 

	if (document.f.email.value == "") {
	  window.alert("Your email address?");
	  document.f.email.focus(); return false; }	
	if (!validEmail(document.f.email)) 
	  return false; 

	if (!document.f.comments.value) {
	  window.alert("Comments field can not be empty.");
	  document.f.comments.select();
	  document.f.comments.focus(); return false; } 
	  
	return true;
}