Could just get the query value from $_SERVER["QUERY_STRING"] and then explode the value with the period which is seperating both values in your example
What you want to do is take a look at $_SERVER['QUERY_STRING']. Explode the query string by . to get an array of values. You can then set up the appropriate variables. Keep in mind you'll also probably want to do some validation on the data to ensure it's in the format you need.
?xyz=123? This will form a key/value pair that you can access using$_GET.