This cache will help with your alpha/numeric challenge.
Your mission, should you accept it, is to use all the skills you have honed and sharpened to locate GZ. Once you have done this you must avoid detection at all costs. Muggle eyes are everywhere. Do not let them discover your mission. If you are captured you will be on your own and all knowledge of your mission will be denied. The objective is to find the cache container located at gz. Duh.