function isFieldEmailAddress(poField, psCaption) {
		re = /.+@.+\..+/ ;

		if (!re.test(poField.value)) {
			alert(psCaption);
			poField.focus();
			return false;
		} else
			return true;
	}

	function isFieldEmpty(psCaption, pField) {
		if (pField.value=="") {
			alert(psCaption + " necesita un valor, por favor llene este campo primero.");
			pField.focus();
			return false;
		} else
			return true;
	}
  
	
	function validateform(f)
	{
		b = true;		
		b = b && isFieldEmpty("El campo Nombre y Apellido", f.nombre);		 
		b = b && isFieldEmpty("El E-mail", f.email);
		b = b && isFieldEmailAddress(f.email, "Por favor introduzca un email valido-");	
		if (document.getElementById("radio").checked==true ) {
		b = b && isFieldEmpty("Telefono", f.telefono); }
		b = b && isFieldEmpty("Comentarios", f.comentarios);		
		return b;		
	}
	
	function checkcontact()
	{
		if (document.getElementById("radio").checked==true ) 
		{
			document.getElementById("telefono").style.visibility="visible";			
		}	
		else
		{
			document.getElementById("telefono").style.visibility="hidden";
			document.getElementById("telefono").value=""; 
		}
	}
	
	function blockNonNumbers(obj, e, allowDecimal, allowNegative)
{
	var key;
	var isCtrl = false;
	var keychar;
	var reg;
		
	if(window.event) 
	{
		key = e.keyCode;
		//alert(key);
		isCtrl = window.event.ctrlKey
	}
	else if(e.which) 
	{
		key = e.which;
		isCtrl = e.ctrlKey;
	}
	
	if (isNaN(key)) return true;
	
	keychar = String.fromCharCode(key);
	
	// check for backspace or delete, or if Ctrl was pressed
	if (key == 8 || isCtrl)
	{
		return true;
	}

	reg = /\d/;
	var isFirstN = allowNegative ? keychar == '-' && obj.value.indexOf('-') == -1 : false;
	var isFirstD = allowDecimal ? keychar == '.' && obj.value.indexOf('.') == -1 : false;
	
	return isFirstN || isFirstD || reg.test(keychar);
}