function validate_bothrequired(field,field2,field3,alerttxt)
{
with (field)
{
if (value.length == 0)
  {
  with (field2)
	{
	if (value.length == 0)
	{
	  with (field3)
		{
		if (value.length == 0)
		{
			alert(alerttxt);return false}
		}
	}
	}
	}
else {return true}
}
}

function validate_form(thisform)
{
with (thisform)
{
if (validate_bothrequired(street,town,postalcode,"Please enter your street, town/city, or your postalcode.")==false)
  {street.focus();return false}
}
}