var field_length=0;
function next(obj,event,len,next_field)
{
	if (event == "down")
	{
		field_length=obj.value.length;
	}
	else
	{
		if (event == "up")
		{
			if (obj.value.length != field_length)
			{
				field_length=obj.value.length;
				if (field_length == len)
				{
					next_field.focus();
				}
			}
		}
	}
}