Security falls under my job as well. I think the majority of my job is in the gray rather than black/white. We have a generic building use policy but every situation calls for interpretation. One woman's perfume is another patron's obnoxious odor, for instance. In terms of incident reports, my campus's policy (once I turn an incident over to police) is to let the police department handle it. Minor offenses (staff training or patron education) are left up to me.
Gray areas are probably best categorized by issues relating to:
#annoyance (lurking, talking, in general making someone uncomfortable)
#group study areas
Black & White areas are characterized by actual safety. If a person feels threatened or IS threatened, the policy is black & white. We call for the police on campus to intervene.
As to how strictly our building adheres to the policy … I'm frequently frustrated at the "not my job" mentality that flows from some (not all). Security is considerably easier when everyone participates in enforcing policies or "nipping it in the bud" before a problem escalates.