7d7a304b__Storm_Center_Diary_2012_10_06__Purpose
[ID] CIP-006-4d [Description] Cyber Security - Physical Security of Critical Cyber Assets [Purpose] 
This standard is intended to ensure the implementation of a physical security program for the protection of Critical Cyber Assets. This include the implementation of physical controls like special locks, walls, biometric and the monitoring system checking all those controls for anomalies.
InfoSec Handlers Diary Blog - Internet Storm Center Diary 2012-10-06
Purpose