If you're looking for contracting jobs that require a security clearance, it's important to know the rules and restrictions you'll be working under. While no employer expects you to know it all before being hired, having information handy will show that you've done some research and care about the industry. Below you'll find a recent release from the OPM regarding contractors and inadvertent exposure to classified materials.
NOTICE TO CONTRACTORS CLEARED UNDER THE NATIONAL INDUSTRIAL SECURITY PROGRAM ON INADVERTENT EXPOSURE TO POTENTIALLY CLASSIFIED INFORMATION IN THE PUBLIC DOMAIN
Contractors shall not, while accessing the web on Contractor's unclassified systems, access or download documents that are known or suspected to contain classified information. Classified information, whether or not already posted on public websites, disclosed to the media, or otherwise in the public domain remains classified and must be treated as such until such time it is declassified by an appropriate U.S. government authority. It is the responsibility of every Contractor to protect classified information and to follow established procedures for accessing classified information only through authorized means.
Contractors who inadvertently discover potentially classified information in the public domain shall report its existence immediately to their Facility Security Officers (FSO). Companies are instructed to delete the offending material by holding down the SHIFT key while pressing the DELETE key for Windows-based systems and clearing of the internet browser cache. Subsequently, administrative inquires and adverse reports are not required. These procedures apply only to the inadvertent exposure to classified information in the public domain.