I am guessing that its a low security area or something like that.
There's no such thing on a military base....
You have either a standard installation area where anyone with base assess privileges can access, or a Restricted area (flight lines, etc) where a specific access permit (commonly called a Restricted Area Badge) is needed.
A major part of the land on DM is covered under Restricted Access (The AMARC area is one, as well as some of the unused desert areas due to unexploded ordinance dating as far back as WWII...). There is a paintball field on base, as well as a training area for the SFS.